Will Kei Tanaka, Who Has Made a Practice of Building Habits, Rank a Smart Bath Mat Among His "Three Sacred Treasures"?

Before the scoring, the MC asked Tanaka how habit-building has felt for him personally. Tanaka said that, judging only by his results, he may look stoic, but he isn't. He got to the point of building habits this thoroughly step by step, and he has failed about 30 times along the way. But once he learned how to build habits, he became able to take on the things he wanted to do, like exercise and study, one step at a time. He feels that habit-building is "truly all-purpose and useful for all sorts of things," and he believes this comes across, to some extent, to the people who follow his content.

The first item is a pair of Shokz bone conduction earphones. The brand offers models such as the OpenRun and the communication-focused OpenComm, and Tanaka says he uses several of them for different purposes.

Tanaka's routine is to wake up at 3-something in the morning and go running, cycling or swimming. The earphones are especially useful when he swims. Normally he connects them to his smartphone via Bluetooth and can listen to anything: YouTube, radio, podcasts, music. But Bluetooth doesn't work underwater. This model lets you load music onto the device itself and play it, so it works in the pool. Riding an indoor bike is fine, but in the pool you have time on your hands. In Tanaka's case, he swims about 260 laps, which takes roughly two and a half hours. Since it takes up a large block of his day, he figured he might as well study at the same time, so he loads music and learning content onto the earphones and listens to them.

He also values their durability. They have an IP68 waterproof rating, and while noting that the manufacturer doesn't recommend it, he said he has accidentally put them through the washing machine many times and they never broke. Some people get on well with separate wireless earbuds, but many didn't suit Tanaka. Because the left and right sides are connected, they don't fall out and can withstand vigorous movements like turns. They're light, and the battery lasts about eight hours, so even if he forgets to charge them two or three times, they'll still last around three days. Tanaka says that someone who exercises for about 30 minutes a day could probably go about half a month without charging them.

The second and third items are software on his smartphone. The second is ChatGPT. Tanaka subscribes to the Pro plan, paying close to 30,000 yen a month.

According to Tanaka, in his current investment business he manages about 300 billion yen. At his previous employer, Goldman Sachs, he managed around 400–500 billion yen, and work on a scale that a team of about 70 people handled at the company before that is now run by about five people. Part of that difference, he says, comes from the power of AI. With Pro he can use Deep Research as much as he likes, so ChatGPT is producing reports in the background even while he exercises or sleeps. If he wants to read them closely, he does; if he wants a summary, he has it summarize them.

Tanaka positions ChatGPT not as a search tool but as a "thinking partner." Now past 40, he has enough experience to form his own hypotheses. Rather than creating something from zero, he is good at expanding a single hypothesis into 10 or 100, so when he poses a question, he has it list out the possibilities. When he needs to adjust how he speaks for different settings, such as a talk for junior high school students versus a radio appearance, he has it instantly draft a script showing how his usual talk would sound for middle and high school students. Because Tanaka makes many media appearances and posts a lot of content, there is a great deal of information about him online, and he said that when it learns from that, "it gets closer to being a clone of me." For documents like contracts that run 100 pages and take two to three hours to read, he first grasps the outline in five minutes and then reads only the parts he wants to. Thirty thousand yen a month is expensive, but by Tanaka's calculation, considering that he used to employ people earning 3 million yen a month, it costs him one-hundredth as much.

Asked why he chose ChatGPT, Tanaka replied that he uses several AIs for different purposes. ChatGPT serves as something like his clone. He uses Claude to manage work, having it systematize routine tasks and build systems shared by the five or so members he works with. Gemini is good at picking up information online, such as about restaurants, so he uses it for research and also to cross-check ChatGPT. That said, ChatGPT is his main one.

The third item is the voice input software Superwhisper. Because of his job, Tanaka writes a lot of approval requests and presentation materials. He has also kept diary-like records, notes on what to say on the radio, and memos of ideas as they come to him. Now, whenever it's okay to speak out loud, he has almost entirely stopped typing by hand and does everything by voice.

Tanaka cited three advantages. The first is how smooth the input is. With typical transcription apps, you have to paste or cut the transcribed text somewhere. Superwhisper can be built in as one of the keyboard's Japanese/English switch buttons, so in any situation where you enter text, you just press the button and speak. The second is customizability. The iPhone's built-in voice input captures every word you say, but Superwhisper can remove fillers like "um" and "uh" from the start, and it can also turn spoken language into written language for emails. Tanaka himself doesn't use that feature because he wants to keep things close to the original, but he says you can also use it to translate as you record. Third, it can work offline in certain environments. By his own feel, Tanaka says it lets him get things done in about one-fifth to one-tenth of the time it takes to write by hand.

He also tried other tools, such as Aqua Voice. In the end, someone he respects said, "I've tried them all, and this one's the best," so he tried it without thinking too hard, and it really was good. That's how he came to choose it.

After hearing the three items, Cheng said that healthcare ultimately comes down to lifestyle habits like diet and sleep, and asked Tanaka, as a habit-building pro, to point out anything that could be improved without holding back.

Scoring is based on three criteria, each worth 5 points, for a maximum total of 15.

1. Ease of adoption: Is the barrier to getting started low?
2. Systematization: Is it part of your daily routine, in a form you can keep up?
3. Perceived effect: Do you actually get a sense of results?

Cheng first made clear that the product isn't aimed at Tanaka, who already manages his weight, but at people who, like Cheng himself, are too busy to manage their weight. There's a preconception that weight management requires effort, but could it be managed almost automatically? That is issin's challenge, and the company calls it "Weight Auto-Care."

Cheng's early career had nothing to do with healthcare. He worked on businesses that create family memories at home for a family of five, such as the projector-equipped light "popIn Aladdin" and "Suika Game." Meanwhile, he threw himself into work in his 30s, and his own health checkup results went steadily downhill. During that time, his father died suddenly. His father had lost weight abruptly without any pain, and because there was no pain, they assumed he simply had no appetite. Then, during the pregnancy with their third child, his wife's pregnancy-related symptoms put her in a dangerous situation. Cheng recalls that what these three things had in common was weight management. Creating family memories is good, but he wanted to protect his family's health, so at 40 he resolved to start a healthcare business.

The conclusion Cheng arrived at was to embed weight management itself into daily life. When the company surveyed people about "why they don't use a scale," many men answered that it was "a hassle," and many women said they "don't want to see the numbers in the first place." According to Cheng, people who can manage their weight diligently like Tanaka make up 10 to 20 percent at most; the remaining 80 percent either find it a hassle or don't want to see the numbers, and the busier people are, the lower it falls on their list of priorities. After testing where people could do it every day without thinking about it, the answer was the bath mat. Coming out of the bath, you're nearly undressed, and it's said that weight is best measured at the same time each day, so he considered this the best spot.

Think of the product as a scale beneath a bath mat. Since tastes in bath mats vary, the company offers its own designs as well as collaboration designs with Pokémon and a design featuring the footprints of SUPER EIGHT's Shingo Murakami.

Cheng says the app itself isn't much different from those of typical smart scales. The difference is that it uses Wi-Fi rather than Bluetooth, so you don't have to bring your smartphone into the bathroom each time; just step on and your record is saved. It can record all the standard metrics, such as weight and body fat percentage.

However, it's hard to look at detailed graphs and understand everything. Since weight fluctuates daily due to meals and other factors, the company decided to show whether your changes are trending in a good or bad direction. Drawing on its data from 170,000 people, it uses a meter like a car's eco-meter so you can see the trend at a glance. Cheng explained that it's like how anyone can drive along with an eco-meter regardless of their driving skill.

For cases where things aren't going well, there's the personal healthcare AI "Welly." Weight changes often happen gradually, especially rebound weight gain, so they're hard to analyze on your own. Welly notices changes before you do and alerts you. Since alerts alone are meaningless, it also helps infer the background: whether it's stress, or whether a change in lifestyle has changed how you eat. And so that people can exercise at home even on hot days, rainy days or days when they're tired from work, the company has also introduced a system that uses Suika Game to let you play while moving your body in front of a camera. Cheng explained that it's the same idea as walking without thinking about it while playing Pokémon GO.

According to Cheng, the product is already used by 170,000 people. The main buyers are in their 30s to 50s, but since it's a bath mat, family members use it too: child users exceed 10,000, and users 65 and older also exceed 10,000. Family members are distinguished by weight difference; with a difference of 2 kg, readings are sorted automatically. When weights are close, both people are notified and asked to choose which one it was.

It covers everyone from newborns to people in their 90s. There's a weight management mode for each: a mode for babies and children that checks whether they're growing well, a maternity mode for managing weight during pregnancy, a general diet mode, a health maintenance mode, and a body-building mode for people who do strength training. Cheng also views data from his mother in China on the same smartphone and can check that her weight isn't suddenly dropping the way his father's did. It also supports pets.

Cheng concluded by saying that he doesn't think of the Smart Bath Mat as just a scale. Most people don't like the word "management" because it implies effort. So the Smart Bath Mat and Welly take on all the work of managing, and he wants to protect users' health. That is Cheng's argument.

Before scoring, Tanaka asked four questions.

The first was whether the bath mat part is a dedicated component. Cheng answered that it is. Measuring body composition requires passing a weak electrical current through the body, but electricity doesn't pass through an ordinary bath mat. So they use conductive fibers, and this part incorporates patented technology. Tanaka said that the 15 data items included things like skeletal measurements, so he had been curious how they were measured.

The second was about support for people who exercise at near-athlete levels. According to Tanaka, expensive body composition monitors have a standard mode and an athlete mode. Cheng replied that because the reference data differs between the general population and athletes, the product also has an athlete mode that users can select.

The third was how to make use of metrics other than weight. Even if you're heavy, it may not be a problem if you have a lot of muscle mass. Tanaka asked whether it gives advice according to goals such as wanting to build muscle or simply wanting to lose weight. Cheng replied that Welly has a general AI chat function and gives advice tailored to your past data and the mode you've chosen. For body-building, it recommends eating more protein; for older people, it checks not only for sudden weight loss but also whether muscle mass is dropping along with it.

The fourth was battery life. The official figure is about three months for a family of five. It depends on how often it's used, but in Cheng's household it has lasted about six months.

The price is 19,800 yen. Cheng said that there are plenty of cheap scales, but this is not a scale; it's a product and service that protects your family's health, and he considers the price reasonable. The AI chat is included in the price, and all basic features can be used for free. There is a separate plan for those who want to use certain extended features.

Tanaka scored it 5 points for ease of adoption, 5 points for systematization and 4 points for perceived effect, for a total of 14.

On ease of adoption, Tanaka prefaced his comments by saying, "This might sound staged, but I'm really not pulling any punches," and talked about seriously dieting about 15 years ago. What he felt mattered most then was "recording," which comes even before controlling diet or exercise. It's taken for granted now, but back then the term "recording diet" didn't even exist yet. Once you record, exercise and diet naturally start to come under control. What he used at the time was Nintendo's Wii Fit board, which had the same concept. But turning on the game console, launching the software and getting into measurement mode took about three minutes every day. It had a system for keeping it fun, but that was about as smooth as it got. With the Smart Bath Mat, you always step on it when you get out of the bath. Tanaka showers every day, so he's guaranteed to pass over it once a day. That naturalness, he said, is why he gave it full marks.

In response, Cheng said he had seen somewhere that Wii Fit was the best-selling scale in the world. But fun doesn't last unless you're conscious of it. He thought at the time that both fun and unconsciousness were needed, judged that unconsciousness was easier to build into daily life, and arrived at the bath mat.

On systematization, Tanaka prefaced his comments by saying that the most important thing in habit-building is whether you can keep it up, and he named three points. The first is automatic recording via Wi-Fi; with a method where you launch an app via Bluetooth to record each time, people drop off. The second is automatic family member identification; many scales require you to switch them on and select "Who is being measured?" but this one doesn't. The third is the battery. When Tanaka used an Apple Watch, he had to charge it every day, but the smartwatch he uses now can go about two months without charging. The Smart Bath Mat is officially rated at three months for a family of five, so for one or two people it might last about six months. It also avoids the dropout factor of finding it a hassle to go charge it. Tanaka praised it, saying he felt it was the result of eliminating everything that gets in the way of a system that fits into daily life.

On perceived effect, Tanaka noted that he hadn't used it continuously, so his evaluation included some imagination. He then said that the "weight myth" isn't very healthy. Lighter isn't necessarily better, and heavier isn't necessarily worse; what matters is what's inside. Since about 15 data items are measured, you can tell that being heavy isn't a problem if it's due to muscle mass. He also praised the function that automatically detects and alerts you to abnormal values, which ordinary scales rarely have. He also speculated that it's probably a system where, for each person's desires, such as not wanting to cut back on food or wanting to exercise as little as possible, the AI chat offers suggestions with gradations rather than black-or-white answers.

He deducted one point because he himself is "too much of a special case" and can manage on his own. From the perspective of someone about to start working on their health, he thinks it would deserve 5 points, Tanaka explained.

Cheng acknowledged that perceived effect is the hardest point. Changes in the body mean completely different things depending on age. For people in their 30s and 40s, dieting or body-building is typical, but in old age, sudden weight loss is a bad sign, and for children you want the opposite: steady weight gain. The company is working with university researchers on weight management for older people and during pregnancy. But lifestyles vary from person to person, and making the best suggestions for each person's goals will remain an ongoing research theme, he said. He also said he wants to eventually be able to meet the standards that professionals demand.

Asked for suggestions to make it even better, Tanaka said nothing much came to mind immediately, but he raised two directions. One is wider awareness. The other is connection with games. Tanaka believes Wii Fit sold as well as it did because the goal of playing a game came first, and you could manage your weight as a side effect of exercising. The Smart Bath Mat feels to him like it's ordered the other way: you start by having it watch over you, and a game is attached to that. A shift in perception that conveys a message like "it's fun for the whole family" might be good. His assessment was that this isn't a problem with the service itself, and that there seem to be plenty of systems for enjoying it and keeping it up.

Cheng agreed with this point. He has been running the company for about four years, and he says the hardest thing about healthcare is that you mustn't make healthcare the goal. If you do, people quit once they achieve it, as with dieting, and they also quit before achieving it. Like walking as a side effect of walking the dog or playing Pokémon GO, what ends up being easiest to sustain is having something fun as the goal and getting healthcare done along the way. There is still plenty of room for ingenuity in this area, Cheng said.

Finally, asked who he would recommend it to, Tanaka prefaced his answer by saying he thinks it's for everyone, then named three groups.

The first is beginners. Tanaka himself has tried building habits, not just around weight, and has gotten reasonably good at it, but it took him about 15 years to get there. He wants to recommend it to people who don't want to spend that much time and want to start casually, today, without feeling bad about it. The second is people who watch over someone other than themselves. Reflecting the founding idea of watching over one's family, he cited parents who want to watch over children under 10, and people in their 30s and 40s caring for family members in their 70s and 80s. The third is adolescents. Many people struggle with weight, appearance and lookism, so he said he hopes it conveys that numbers can mean many different things. In the end, it applies to all generations, but Tanaka's overall assessment was that it seems to offer the options and flexibility for people at different stages of life to use it in different ways.

Cheng said that people in their 30s and 40s at the peak of their working lives tend to deprioritize their own health even when they want to look after it. He himself is "lazy," he said, but having improved his own health checkup results, he has proven that using it lets you manage your weight automatically. With that, he wrapped up his pitch.