Toshiyuki Masui

Toshiyuki Masui (born July 11, 1959, in Nishinomiya, Hyogo) is one of Japan's most influential user-interface researchers and inventors. He earned his undergraduate degree in Electronics Engineering from the University of Tokyo (1982) and a master's in the same field (1984), and later a Ph.D. in Engineering. His career spans many of the leading names in computing: Fujitsu's semiconductor division (1984–1986), Sharp (1986–1995), a visiting research stint at Carnegie Mellon University (1989–1991), Sony Computer Science Laboratory (1996–2003), and Japan's National Institute of Advanced Industrial Science and Technology / AIST (2003–2006).

He is best known for inventing POBox, a predictive Japanese text-input system developed at Sony CSL that became the standard input method on Japanese feature phones. In 2006 he was recruited by Apple (reportedly at the invitation of Steve Jobs) where, from 2006–2008, he worked on the iPhone's Japanese input — the flick input method now standard on virtually all Japanese smartphones.

In 2009 he joined Keio University's Faculty of Environment and Information Studies as a professor, a post he held until 2025; he is now Professor Emeritus at Keio and a Guest Professor at the Open University of Japan (2023–present). Over his ~16 years at Keio, his lab produced numerous founders and researchers. From 2014 he served as CTO of Nota Inc. (now Helpfeel Inc.), where he invented or co-created the company's flagship products — Gyazo (screen/image capture, with roughly 10 million users worldwide), Scrapbox / Helpfeel Cosense (collaborative knowledge base), and Helpfeel (a search-based AI-FAQ help system). He stepped back from the CTO role around 2021 and now serves as the company's Technical Fellow.

Masui's standing as an "angel investor" reflects his role as a senior technologist and mentor in Japan's startup ecosystem rather than that of a high-volume professional VC. He is a Fellow of the Information Processing Society of Japan (IPSJ) and a long-time advocate of "dogfooding" and inventor-driven product development.

> Note: Masui has not published a formal, written investment thesis. The points above are inferred from his stated philosophy and career focus; treat them as directional, not as quoted fund criteria.

• Invests at the seed stage as an individual angel, in a personal capacity rather than through a fund.
• Natural focus areas align with his deep expertise: human-computer interaction, text input/UI, developer and productivity tools, and knowledge-management software.
• Values invention and original ideas — his public writing and talks (e.g., "アイデア大爆発" / idea-explosion, "Columbus-style invention," and his "富豪的プログラミング" / "wealthy programming" essay) emphasize bold, first-principles product thinking and building tools you yourself use daily (dogfooding).
• As a former CTO and long-time professor, he is positioned to back technical founders, including those emerging from academic / research backgrounds.