kensaurus合同会社 — kensaurus LLC

Tokyo studio in Shibuya building software, mobile and web apps, IoT systems and 3D, photography and video, and the revival of empty buildings and rural places. Founded 2025-06-06 by Kenji Sakuramoto. Operating in English, Japanese, Chinese, Thai, Vietnamese, and Malay.

What we ship

Everything below is public and running today unless it is marked in development: mobile apps, web apps, a live camp dashboard and AI tools.

Live projects

  • Work & Camp — 嬬恋牧場Work&Camp

    A mountain campsite with an office, run by us. Tsumagoi Work&Camp is a campground at 1,444 m in Tsumagoi, Gunma, on a former ranch with no houses within 7 km. Guests pitch a tent anywhere on the field, work from an office on fiber internet, and end the day by the fire. 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.

  • Mushi Mushi — 虫虫

    A report-a-bug button for apps, with AI that sorts the reports. Error-tracking tools only notice problems that crash the app. Mushi Mushi catches the ones people notice, like a button hidden behind a header, by adding a small report-a-bug button to any website or app. AI rates each report, groups duplicates and points to the likely cause in the code, and it can draft a fix. A person reviews each fix, unless you turn on verified merge, which merges a small fix on its own only when a test proves it works. It is open source, with a free hosted plan. (GitHub)

  • Solo Boss — 一人社長

    Solo Boss keeps the books for one-person companies in Japan and takes them through to the tax filing. Bank lines and receipts become journal entries with AI help, every number links back to its receipt or bank line, and checks catch mistakes before you file. Already use other accounting software? Import its journal instead. It is free for now.

  • kenji skills — エージェント用スキル集

    Step-by-step playbooks that keep AI coding assistants on track. AI coding assistants such as Claude Code, Cursor, Codex and Gemini often stop halfway, or say a job is done when it is not. kenji skills is a free, open-source set of written procedures they follow step by step, from fixing a bug to shipping a release, and a separate AI checks that the work is really finished. We use it on every project we run, and it installs with one command. (GitHub)

  • Ranch Plan — 牧場計画

    The business plan behind Tsumagoi Work&Camp. Before the camp opened, we published its business plan as an interactive website: what the old ranch building would become, what it would cost, and which permits each service needs. The six-page plan we prepared for the bank and insurers is part of it.

  • Project Ledger — 日報台帳

    A daily work log for a team’s projects. Project Ledger is a work diary for teams: each person records what they did and for how many hours, project by project. The public page shows a real delivered client project, a shift-management system, as the example.

  • Wedding Kiosk — 結婚式受付端末

    A guest kiosk and RSVP page made for one wedding. Made for our founder’s own wedding dinner: a tablet at the entrance where guests could check the schedule, read how the couple met and look through their photos. A separate page collected RSVPs for the beach ceremony. The live site is password-protected, for invited guests only.

  • Skin Analysis — 肌診断

    Take one selfie in natural light and get scores for more than 20 skin concerns, such as pores, hydration and texture, plus 4 to 6 care tips. Claude reads the photo. It is free, needs no account, and the photo is deleted after the analysis.

  • ProjectFlow — プロジェクト管理

    Projects, estimates, invoices and delivery in one place. ProjectFlow is a management dashboard for teams that deliver work to clients. It follows each job from estimate to delivery and invoice, so nobody has to piece the picture together from spreadsheets and chat threads. It works in English and Japanese.

  • glot.it — タイ語学習

    A Thai learning app with an AI tutor. glot.it teaches Thai to people starting from zero, whether for a trip, a Thai partner or family, or work. It covers the Thai script, the five tones and everyday speaking, with an AI tutor you can talk to. It runs in the browser and on iPhone and Android. (App Store · Google Play)

  • help her take photo — 写真撮って

    help her take photo links two phones. One is the camera, and the other shows that camera’s view live, so the person being photographed can see the shot and direct it before it is taken. It is made for couples and friends who travel together, on iPhone and Android. (App Store · Google Play)

  • yen-yen — 家計簿

    yen-yen is a household money book that two people, or a whole family, keep together. It never asks for your bank login: add spending by hand in a few seconds, or paste a bank statement and AI sorts the lines for you to check before anything is saved. Each expense goes into one of four kakeibo groups, so by the weekend you can see where the money went. On iPhone and Android. (App Store · Google Play)

  • Konte — コンテ

    Plan and make an 8-second AI video, step by step. Konte (Japanese for storyboard) walks you through a short AI video the way a film crew works: pick a template, write the scene, choose the camera and mood, review, then render. Google’s Veo makes the video with your own Gemini API key, so Google bills you directly and Konte charges nothing. It is a prototype, first built for our partner babuu AI.

  • the wanting mind — 渇望する心

    A book about why we want, free to read online. Why do people want, and why do some take while others give? the wanting mind is a 36-chapter book by our founder that follows that question through neuroscience, economics, philosophy and anthropology. It is free to read on the web and in the iPhone and Android apps. (App Store · Google Play)

  • lets-talk — 会話の練習

    Practise difficult conversations with an AI coach. lets-talk helps you work out what to say when a message is hard to answer, from an upset boss, partner or friend. Paste their message to see their side and get replies you could send, write your own reply and get it scored, or rehearse the whole chat with an AI that plays the other person. On iPhone, Android and the web, with no account needed. It is a practice tool, not therapy. (App Store · Google Play)

  • Hear, Hear — 録音・文字起こし

    Live transcription in your browser, no account. Hear, Hear turns speech into text while people talk, using the browser’s own speech recognition (in Chrome, that means Google’s). Every line keeps its timestamp, and tapping a line replays that moment. There is no account, and the recordings and transcripts are saved only in your browser. In this public version a recording can run up to five minutes.

In development

  • Bento — 弁当

    Bento is a prototype workspace for planning, collecting material, making things with AI, reviewing and shipping, all in one loop. Development is paused, and it is not open to the public right now. (In development)

Writing

  • 止めずに、少しずつ新しくする。古いPHPシステムのアップグレード (kensaurus, 2026-10-22)
  • Upgrading an old PHP system without switching it off (kensaurus, 2026-10-22)
  • PHPの重大な脆弱性 php2shell:対象と今日やること、そして年末の期限 (kensaurus, 2026-10-22)
  • php2shell: which PHP versions are hit, what to do today, and the year-end deadline (kensaurus, 2026-10-22)
  • 声調ひとつで「馬」が「犬」になる。自分の言葉で覚えるタイ語アプリ glot.it (kensaurus, 2026-10-16)
  • One tone off and “horse” becomes “dog”: why I built glot.it for Thai (kensaurus, 2026-10-16)
  • 登録なしで、会話を時刻つきの文字に残す。ブラウザの文字起こし Hear, Hear (kensaurus, 2026-10-16)
  • Keep a conversation as timed text, with no account: Hear, Hear (kensaurus, 2026-10-16)
  • 「ちょっと見せて…消して」をなくしたくて作ったカメラ (kensaurus, 2026-10-16)
  • A camera for the “let me see… delete it” moment (kensaurus, 2026-10-16)
  • 「完了しました」で止まるエージェントに、手順書と完了の関門を渡す (kensaurus, 2026-10-16)
  • My agents kept saying “done” when they weren't, so I wrote the playbooks down (kensaurus, 2026-10-16)
  • 言いにくい返事を、送る前に練習する lets-talk (kensaurus, 2026-10-16)
  • lets-talk: rehearse the message you're dreading (kensaurus, 2026-10-16)
  • このアプリたちを作っている人のこと (kensaurus, 2026-10-16)
  • Who makes these apps, and why (kensaurus, 2026-10-16)
  • エラーにならないバグの報告を、マージ前の修正案まで。Mushi Mushi (kensaurus, 2026-10-16)
  • From “this is broken” to a fix PR I merge by hand: Mushi Mushi (kensaurus, 2026-10-16)
  • ひとり法人の決算ツールを作り、自分の申告で間違えて直した話。一人社長 (kensaurus, 2026-10-16)
  • I built a year-end filing tool for my one-person company, and it got my own filing wrong (kensaurus, 2026-10-16)
  • 「人はなぜ欲しがるのか」を追う、読んで聴ける本 the wanting mind (kensaurus, 2026-10-16)
  • the wanting mind: a book about why we want, to read, hear and ask (kensaurus, 2026-10-16)
  • 銀行とつながない、夫婦で続ける家計簿 yen-yen (kensaurus, 2026-10-16)
  • yen-yen: a money book for two that never touches your bank (kensaurus, 2026-10-16)
  • 行間を読めるまで何年もかかった私が、練習アプリに「話し方の背景」を入れた理由 (note, 2026-10-16)
  • 旅先の写真係として叱られてきたので、シャッターを撮られる人に渡すカメラを作りました (note, 2026-10-16)
  • 家族と同じ家計簿をリアルタイムで見たくて、Expense IQ から自分の家計簿アプリに移りました (note, 2026-10-16)
  • From "this is broken" to a fix PR I merge by hand (DEV, 2026-10-15)
  • 空置されていた牧場の建物を、仕事ができる場所にするまで (note, 2026-10-15)
  • 管理画面の中身を、もう少し:朝の画面、売店、Wi-Fi、集客 (note, 2026-10-15)
  • 半径7kmに民家のない、標高1,444mの元牧場です。 (X, 2026-10-14)
  • エラーにならないバグ(押しても反応しないボタン、12秒かかる画面)を拾うOSS、Mushi Mushiを作っています。 (X, 2026-10-13)
  • 「このバグを直して出して」で手順が走る、エージェント用スキル集の中身とインストーラの安全設計 (Zenn, 2026-10-13)
  • 「夕ご飯作った。食べた。それから、無事かどうか考えてた。」にどう返す? (X, 2026-10-12)
  • 言いにくい話を、送る前に練習するアプリを作っています (note, 2026-10-11)
  • タイ旅行の前に、屋台で注文できるくらいのタイ語を。 (X, 2026-10-11)
  • KENSAURUSでつくっているもの (X, 2026-10-10)
  • 山のキャンプ場を、ひとつの管理画面で動かしている話 (note, 2026-10-09)
  • 山のキャンプ場を夫婦二人で回すために作った管理画面の話を書きました。 (X, 2026-10-09)
  • ESP32・カメラ・Wi-Fi・決済を、山のキャンプ場の管理画面ひとつにまとめた (Zenn, 2026-10-09)
  • 銀行連携なしで、夫婦で続けられる家計簿アプリ「yen-yen」をつくりました (note, 2026-10-08)
  • ひとり法人の決算ツールを作り、自分の申告で間違えて直した話 (note, 2026-10-08)
  • 「人はなぜ欲しがるのか」を追う、無料で読める本を作っています (note, 2026-10-08)
  • 標高1,444mの元牧場で、光回線のオフィスとキャンプ場をはじめました (note, 2026-10-08)
  • 山にオフィスを立てた。 (X, 2026-10-08)
  • 「人はなぜ欲しがるのか」を追う本「the wanting mind」を作っています。 (X, 2026-10-08)
  • アプリ内のバグ報告をMCP経由でエディタに渡す仕組みと、その設計 (Zenn, 2026-10-08)
  • Two months ago my wife and I opened a small campground and coworking space on an old ranch in Tsumagoi, Gunma, 1,444 metres up. (LinkedIn, 2026-10-07)
  • Thai has five tones. One slip and "horse" (ม้า) becomes "dog" (หมา). (Bluesky, 2026-09-14)
  • A 147,000-word interactive book as a free SPA, and the stack behind it (DEV, 2026-04-23)

Services

kensaurus operates across 11 business categories: AI / Software / Mobile, Web / SaaS / PWA, IoT / 3D / センサー, 写真 / 映像 / 編集, 記事 / 映像 / 配信, キャンプ / テレワーク / アウトドア, 共同作業 / オフィス / ラウンジ, 空き家 / 改修 / 活用, 地方創生 / 田舎 / 関係人口, SEO / 広告 / 集客, and セキュリティ / PHP / 移行.

Contact

kensaurus合同会社, 東京都渋谷区道玄坂1丁目, Shibuya, Tokyo, Japan. Founded June 6, 2025. Capital ¥1,000,000. Representative: Kenji Sakuramoto (櫻元賢次).