What would you still want to build if you were already a billionaire?

I’ve been returning to this question through conversations with founders, scientists, and investors across Japan and the U.S. It has shaped how I’m thinking about what I may build next.

I remain deeply involved in building Taxa; this newsletter is a place to share the questions and ideas I’m exploring beyond our formal company updates.

People I learned from

• Ben Cera, founder of Polsia, shared lessons from building with agents, going viral, and fundraising. His clearest advice: keep the team small before product-market fit, validate with real behavior, and distinguish early enthusiasm from scalable economics.
• Bill Tai, an early backer of companies including Zoom and Canva, described great founders as people with integrity, agency, ambition, and a compelling story. He also reminded me that enduring technology communities begin with people gathering informally to exchange information and help one another.
• Shubham Yadav, a neurotechnology researcher in Zurich, is developing minimally invasive neural interfaces—including microscopic photovoltaic devices that can travel with immune cells and deliver targeted stimulation without conventional brain surgery. His emphasis was on choosing diseases with genuine unmet need and working closely with clinicians, not pursuing novelty for its own sake.
• Gengxi Lu, whose background spans acoustics, medical ultrasound, and neuromodulation, argued that hardware miniaturization is no longer the main constraint. The harder problem is neuroscience: knowing where, when, and whether to activate or suppress a circuit.
• Professor Naohisa Yahagi pioneered endoscopic submucosal dissection (ESD), a minimally invasive technique for removing polyps and early-stage cancers from the gastrointestinal tract. He explained that many of his inventions emerged from performing countless procedures while also working in emergency care. Today, one of ESD’s biggest challenges is developing flexible robotic systems that can safely navigate difficult-to-reach areas such as the duodenum and colon.

What I read

• Colossus wrote a piece on Mark Zuckerberg, and how he sees himself as a tech scapegoat. https://colossus.com/article/mark-zuckerberg-profile/
• Scientists found that genetically depleting a newborn mouse's cortex and engrafting human cortical organoids (creating "xenocortical" mice) allows human neurons to grow, connect into functional circuits, and influence host behavior, offering a new in vivo platform to study neurodevelopment and model brain diseases. https://www.nature.com/articles/s41586-026-11032-2
• Nature Biotechnology article introduces "Circulatronics," a nonsurgical brain implant technology that uses immune cells carrying microscopic, wireless electronic devices to autonomously travel to inflamed brain regions and enable targeted, light-controlled neural stimulation. https://www.nature.com/articles/s41587-025-02809-3

Conversations and events in Japan

I recently caught up with Representative Furukawa, who was appointed Secretary-General of Team Mirai. We first met before he entered politics, when he was working as an engineer in San Francisco. It was exciting to exchange ideas about how Japan can build its future.

During my recent stay in Tokyo, I spoke at the TECHNIUM Conference alongside Issei Takino of Mujin and Hiroki Koga of Oishii Farm. One theme was how founders can make better use of Japan’s distinctive advantages, including its talent pool and grants for strategic sectors under Prime Minister Takaichi.

A highlight was visiting Kukuku, created by fellow Forbes JAPAN 30 UNDER 30 honoree Fujita-san. It offers Japan’s first dessert-focused tasting menu, and I highly recommend it!