Koki Doi was born into a household full of entrepreneurial spirit — his father ran his own business; his mother worked at the Tokyo Stock Exchange; and nearly every relative was self-employed. Growing up in this environment, he was inspired at an early age. From elementary school on, he knew that he wanted to build a company of his own. A high school trip through New York, San Francisco, and Palo Alto turned that dream into a conviction. He watched American startups reshape entire industries within a few years of founding and came home to Japan asking why that kind of company didn't exist there. He then spent three years at a fast-growing HR startup, visiting university labs and connecting top students with Japan's leading tech companies. As the youngest division head, he took on a wide range of responsibilities, from launching new business units to driving recruitment. Koki founded Morght in 2018. NELL, the company's flagship sleep brand, launched in Japan (2020) and entered the US market as an extension of a long-standing conviction: the sleep industry has spent decades optimizing for sales instead of sleep.

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Japan has the worst sleep quality of any developed nation. That fact wouldn't leave me alone.

Japan also ranks fourth in the world for spending on sleep products. We're investing heavily, and yet Japanese consumers are losing an estimated 20 trillion (Yen) every year to sleep debt, roughly three percent of the GDP. The more you pay, the worse you seem to sleep.

I had to understand why. I read every Japanese book on sleep science that I could find and visited every mattress showroom in Tokyo. I spent full days at Nitori — Japan's largest home goods retailer — watching how people actually bought mattresses. The pattern was the same everywhere: a woman would lie down on a display bed, sink into the softness, and say, "This feels amazing!" The man would pull out his wallet. Sale made.

I noticed that stores deliberately engineered this moment. The mattress that feels the best in a showroom — the one designed to let you sink in and feel cradled — is often the one doing the most damage at home. Back pain. Stiff shoulders. Years of poor sleep. People even stop connecting this problem to their mattress and look for other culprits.

The sleep industry was optimizing for sales, not sleep.

In the US, I saw the same problem at a larger scale. Back pain is one of the leading health issues that Americans face. And yet the market is dominated by soft, memory foam — chosen by customers based on how they feel for thirty seconds on a showroom floor. There are more than 200 mattress companies, and not one has really solved for what happens after a thousand nights.

NELL was built to fix what everyone was ignoring.

We made two early decisions that became the constraints that everything else was built around: 1) we would only sell online, and 2) we would make one mattress.

While not having a showroom sounds like a disadvantage, it turned out to be the most clarifying decision we made. Because the customer isn’t touching our product before they buy, we can't build for the showroom moment. We don’t engineer the soft, seductive first contact and hope people won’t notice the trade-offs at home. Our product has to be honest. It has to perform the same on the five hundredth night as it does on the first.

Making a single mattress instead of a lineup was the harder constraint. Most brands offer soft, medium, and firm mattresses — a way of giving every body type something that "works for them." We refused that path. We attempted to solve the actual problem at the engineering level: how do you create a mattress that promotes healthy sleep posture and natural movement across a wide range of bodies and sleeping styles?

These two constraints stripped away every shortcut. We couldn't hide behind customization. We couldn't offer a "softer option" for people who wanted immediate comfort. We had to make something that genuinely worked — and prove it, repeatedly, to people who bought our mattresses without ever lying down on one.

The tension between those two constraints shaped everything: the coil structure, the firmness profile, the material choices. The constraint was the product.

When we entered the US market, the question we faced most often was this: why not memory foam?

It's what America knows. It's what is in every store. Billion-dollar companies are built on it. The instinct to match the market — to meet the customer where they already are — is not an unreasonable one. And I understood the appeal. I'd spent years studying why people choose soft mattresses. That first feeling is real. It's genuinely pleasant.

But I'd also studied what happens after that first feeling. When I looked at the customer data, the same pattern we'd found in Japan emerged: customers loved those mattresses for a year, sometimes two. Then, the sagging began. The support disappeared. And people stopped connecting their worsening sleep — the back pain, the mornings that felt worse than the nights before — to the mattress underneath them.

Although we were pushed to soften our product and to create an out-of-box experience that felt more immediately impressive, we held firm.

The Japanese approach to durability is not a marketing concept — it's an engineering standard. It's why Toyota became what it became. A mattress is not a car, but the principle is identical: engineer for the long term relationship, not the first impression. Moreover, memory foam has been commoditized and the price floor compressed. The gap between a $500 mass-market mattress and a $2,000 US mattress now often exists more in perception than reality.

Japanese craftsmanship can close that gap in the right way. We held the line because we believe that the brands that will win the next decade in this market will be the ones that customers trust after year three — not the ones who win year one.

We removed the softness trap.

Almost every mattress in the market — in Japan and the US — is optimized for one thing: the moment of first contact. You lie down; you sink; you feel held. But that response has been engineered. We took it out.

It’s not that comfort doesn't matter — it does. But "soft" and "supportive" have been conflated for too long, and they are not the same thing. The mattress that feels like a cloud is often quietly compressing your spine, collapsing your alignment, and making it impossible to turn naturally through the night. Sleep is not a static state. Your body moves dozens of times while you rest, and a mattress that inhibits that movement is working against you even while you sleep. We built around ease of movement — the naturalness of turning over — rather than the feeling of sinking in.

We also resisted the temptation to expand our product line before the foundation was ready. Recovery wear, pillows, sleep accessories — there's an entire category of products we want to bring to market eventually. We chose not to. In the most literal sense, the mattress is the foundation of everything we're trying to accomplish. Adding anything before that foundation was established would have slowed our growth and been a distraction. It was the right call.

The cuts are the product. What we chose not to add is as much of who we are as what we built.

When I started NELL in Japan in 2020, the US market was already part of the plan. Not someday — from the beginning. The American sleep market is the largest in the world and also the most overdue for disruption. There are more than 200 brands competing over price, softness, and marketing while their customer base deals with chronic back pain and accumulated sleep debt, which most of the market isn't built to address.

In regards to Nell Japan, we plan to expand beyond mattresses to include pillows, recovery wear, products that work quietly in the background of daily life to improve sleep quality. We're also investing seriously in R&D and the clinical evidence that lets us make specific, verifiable claims about what NELL actually does. The goal is not to be another wellness brand with beautiful packaging. The goal is to be the brand customers trust because we've earned it — with data, with durability, with years of excellent sleep.

Our commitment to Japanese craftsmanship and to longevity over immediacy will never change. We make things that last because we believe that the relationship between a customer and what they sleep on should last. That standard doesn't move regardless of where we sell, what we add to the line, or how the market changes around us.

We want to be the Toyota of sleep. That's not a tagline. It's an engineering obligation.

Elon Musk, honestly. There has never been an entrepreneur in history who combines vision at that altitude with actual engineering execution like that.

Smartphone / Claude Code

Jobs to be Done Theory (AKA Job Theory)

Bathing before sleep

Haven't bought it yet, but the experience that surprised me most was NOT A HOTEL.

(Note: NOT A HOTEL is a Japanese luxury concept that reimagines what it means to own a home: you purchase a share of a private villa; it runs as a hotel when you're away; and you gain access to a network of properties across Japan. The category didn't exist before they created it.)

Don't listen to what people say — watch what they do. Read demand from behavior, not words.

Iced Americano.

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