Senior UX Designer based in Tokyo. Seven years at Shopify designing order management and fulfillment systems — sole designer on cross-functional squads, from pitch through execution.
Now building my own tools using AI-assisted development — shipping products independently and rethinking how design and building work together.
Actively looking for product design roles at English-friendly companies in Tokyo. Get in touch: simon.callsen@gmail.com.
Case studies
Rebuilding how stores price shipping, to match how merchants actually think about it
Making it clear how each store location is set up online
Letting stores move stock between locations, so one missing item stops blocking an order
Personal projects
A daily study dashboard that tracks textbook progress, drills vocabulary with spaced repetition, and pulls in anime, news, and generated stories for reading practice.
A Steam Deck plugin that reads Japanese text on screen, looks up each word in a dictionary, and saves them for later study — without leaving your game.
Study tool to practice conjugating Japanese verbs
Hackathon projects
Parse Japanese nutrition labels (栄養成分表示) into a simplified, honest view.
Pick a kanji, see what it is made of, keep exploring. Neo4j + Daytona graph explorer with a pixel UI.
Find the best train station exits for your destination.
An agentic browser-based game.
Background
Designing and shipping personal projects using AI-assisted development
Japanese language studies from Beginner 1 (~N5) to Advanced 5 (~N2)
Designed merchant-facing experiences across shipping labels, multi-location fulfillment, local delivery, pickup and order routing
- Senior UX Designer2023–2025
- UX Designer2018–2023
- UX Intern2018
Graphic Design Advanced Diploma