Individual Developer Studio

Small tools.
Real use.

I build things that remove the small frictions of everyday life.
No bloat. Just the one thing that needed fixing.

Products

Products

Polaris Premium ¥300/mo EN / JP

Polaris

Turn vague ambitions into a clear roadmap through AI conversation, then make daily progress just by checking off actions.

  • AI generates mid-term goals and actions
  • Progress bars keep you motivated
  • Monthly review reports, auto-generated
  • Add to home screen (PWA)
Open App →

Tools

Tools

Small, fast, and solving exactly one thing.

FLOW TASK
FLOW TASK
GTD-based task manager. Capture to Inbox, focus on Today — auto-reset every morning keeps you on track.
Free JP only Open app →
FLOW YOTEI
FLOW YOTEI
No sign-up needed. Share a URL and let people pick a time — scheduling made simple.
Free JP only Try it →
Notipop
Notipop
A Chrome extension that saves selected text to Notion in one click.
Free JP only Get started →
HENSAI
HENSAI
Manage mortgages, card loans, and revolving credit in one place. Visualize your repayment schedule and payoff date.
Free JP only Try it →
SizeKit
SizeKit
Resize & convert images to recommended SNS sizes. Runs entirely in your browser — no uploads, no server.
Free JP only Try it →

Services

Services

Development support for individuals and small teams.

Claude Code Onboarding Support
Help setting up and getting the most out of Claude Code, Anthropic's AI coding tool.
Inquiry Contact →

Playground

Mini Games

Small games built between coding sessions.

Click first to focus · SPACE to jump · Hold for higher jump

Arrow keys or swipe · Merge tiles to reach 2048

Game Center →

About

Who's building this

Kobayan

Kobayan

Tokyo / IT manager by day / indie dev by night

I work as a manager at an IT company. Nights and weekends, I build things I actually want to use.
Not looking to go viral — just making tools that feel good in the hand.
The best moment is when someone uses something I made without thinking about it.

Next.js Firebase Chrome Extensions AI-assisted dev Vibe coding
note → X →