The person who built this place
Sennin Kenji & KENSAURUS
A hermit who runs this campground at 1,444 m and builds apps in the Kotatsu Lounge.
Visit kensaur.us
Who is Sennin Kenji?
He runs Tsumagoi Work&Camp. He built almost all the furniture here himself.
His real name is Kenji Sakuramoto. He runs Kensaurus LLC and builds its apps.
What KENSAURUS makes
A small company that hands Japan's little hassles to AI, so you don't have to deal with them.
Kensaurus LLC · Shibuya, Tokyo · founded June 2025
Exhibit 01
Solo Boss一人社長
Bookkeeping through to tax filing, for one-person companies
Year-end statements, tax schedules and e-Tax / eLTAX files, with a review link for your tax accountant
Free for now
Open Solo Boss
Exhibit 02
Mushi Mushi虫虫
A report-a-bug button for apps, with AI that sorts the reports
Users write one line; the screenshot, page and technical details are attached for them
Open source · free hosted plan
Open Mushi Mushi
Exhibit 03
kenji skillsエージェント用スキル集
Step-by-step playbooks that keep AI coding assistants on track
Ask in plain words, like “fix this bug and ship it”, and the matching playbook runs
Free · open source
Open kenji skills
And more
glot.it · タイ語学習A Thai learning app with an AI tutorWeb · iPhone · Android
yen-yen · 家計簿A shared household money book, no bank loginiPhone · Android
help her take photo · 写真撮ってTwo phones, one camera: the person in the photo directs the shotiPhone · Android
the wanting mind · 渇望する心A book about why we want, free to read onlineFree · web · iPhone · Android
Skin Analysis · 肌診断Skin scores and care tips from one selfieFree · no account
lets-talk · 会話の練習Practise difficult conversations with an AI coachiPhone · Android · web · no account
This site is one of them
Tsumagoi Work&Camp — A mountain campsite with an office, run by us
We renovated the buildings ourselves, built most of the furniture on site, and opened in August 2026. The website, online booking, payments and on-site sensors are all software we wrote.
Book a stay
Hermits live on mist. I also make apps. — Sennin Kenji