Vol. XI · Independent practice · Osaka, since 2014
Kazuaki Iso.
Independent Product Designer & Interface Engineer — shipping interfaces for ambitious teams since 2014.
Chapter 01 — What I do
I design the interface and write the front-end code in the same head — so what leaves my desk is what gets shipped.
Most studios split the work between a designer and an engineer, then lose two or three weeks to a handoff gap. I close that gap by doing both. Every engagement starts as Figma frames, ends as production React and TypeScript, and is reviewed line-by-line by the same person who drew the screens.
The offer is narrow on purpose. I take on product interfaces for SaaS, fintech, and developer tools — the kinds of products where the difference between a 41% lift in activation and a flat line is measured in the first ten seconds a user spends inside the surface. If that's the kind of bet you're trying to place, the conversation usually starts with a 30-minute scoping call.
Every statement of work I sign includes one measurable UX outcome — activation rate, retention, task-completion time, or the equivalent — with a guarantee. If the agreed metric isn't hit at the end of the engagement, the final invoice is reduced by 50%. The clause exists because the work ships, and the clause makes that provable.
Chapter 02 — Selected work
Four recent interfaces, shipped end-to-end.
A small curated index. The full case studies sit behind each plate — process notes, failed iterations, and the post-launch metrics.
Chapter 03 — How an engagement runs
The four chapters of a typical six-week engagement.
Average engagement length is 6.3 weeks. The cadence below is the default — adjusted per project for scope, codebase, and review windows.
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01
Discovery · Week 1
A working week on your codebase, your metrics, and your users. I read the analytics, sit in on three customer calls, and walk the product cold. Output: a one-page brief with the agreed measurable UX metric for the SOW and a written scope of what we will and will not touch.
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02
Build sprint · Weeks 2 – 4
Three weeks of design and front-end build, in parallel. Figma frames ship each Friday for review; a usable branch ships each Tuesday behind a feature flag. You see the interface as it is being made, not after it is finished. Loom walkthroughs replace status meetings.
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03
Review & iteration · Week 5
One full week of structured review against the brief. Two rounds of revisions against the agreed metric, plus a written post-build audit. The component library is updated as a side-effect, so the next team inherits a cleaner system than the one we started from.
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04
Launch handoff & measurement · Week 6
Pair with your engineers for the rollout, write the launch comms for the design side, and set the measurement window. A 30-day post-launch review against the SOW metric closes the engagement. 73% of clients book a second engagement within 90 days of this review.
Chapter 04 — By the numbers
Verified facts about the practice, presented without embellishment.
62
Product launches shipped across SaaS, fintech, and dev-tools since the practice was founded in 2014.
41%
Average reduction in time-to-first-value across the last 14 engagements, measured against client baselines.
4.97/5
Average rating across 47 verified Clutch reviews — top 1% of designers globally.
73%
Of clients book a second engagement within 90 days of the first post-launch review.
- Founded the practice in 2014 after leaving a lead designer role at a Tokyo-headquartered fintech.
- 4.2M estimated end-users across shipped client products.
- Operates as a solo practice from Osaka, with a vetted bench of 4 specialist collaborators (motion, 3D, copy, research) activated per project.
- Cumulative client revenue under contract: $3.8M since 2019, with zero client churn due to missed deadlines.
- Publishes an open-source component library, Iso Primitives, used in production by 600+ teams.
- Personally reviews every line of shipped front-end code — no junior execution layer.
Chapter 05 — A working note
Who this practice is built for, and who it isn't.
A short note from me, Kazuaki — written so we both know whether a conversation is worth the half hour before we get on a call.
The work fits well when the team is between a seed-stage product that has found its wedge and a Series B product that needs to convert that wedge into a repeatable revenue surface. The founder or head of product is still close to the interface, the team is technical enough to read the code I'm handing over, and the metric that matters is already named out loud — activation, retention, completion time, or the equivalent in your domain.
The work fits less well when the brief is "redesign our marketing site," when the team wants a brand system before the product surface is honest, when there's no-one on the client side who will look at the Figma file between Friday and Tuesday, or when the deadline is shorter than three weeks. I won't take a 10-day redesign of an analytics product no-one on my side will be able to defend in six months.
If that filter reads as the right shape, the next step is a single 30-minute scoping call. No slide deck, no qualification script — a working conversation about the surface you're trying to ship and the metric you're trying to move. Book a slot below and I'll send a calendar invite within a working day.
Book a Scoping Call