Available
A trainer for Japan’s written driving exam
A free trainer for Japan’s written driving exams — 外免切替, 仮免 and 本免. Each of its 932 true/false questions carries a verbatim quote from the 教則, the National Police Agency rulebook the exam is written from, so an answer you disagree with can be checked against the source rather than taken on trust.
iOS · iPadOS
What it does
Answer a question and the rule that decides it appears underneath, quoted word for word from the police rulebook the exam is written from, with a translation and the chapter it sits in. Disagree with an answer and you can check it instead of taking it on trust. The Japanese original is one tap away.
All 932 statements are built on the rulebook's own wording rather than paraphrased from it, and every quote is machine-checked against that text. When the rules are amended, a question whose quote no longer matches raises a flag instead of quietly going stale.
The conversion check is 50 true/false questions in 30 minutes and you pass at 45 — a 90% bar on a test where most of the difficulty is in the wording. Gokaku drills only ○/×, the shape of the real paper, and puts the mock exams on the same clock. Never multiple choice.
Each question is tagged with one of seven trap types — a boundary number flipped from 未満 to 以下, an absolute “always”, a quietly dropped exception. Scores are kept per trap, so the pattern behind a wrong answer is visible, not just the count.
208 official signs and road markings, all drawn to the same official geometry rather than collected from mixed sources, with 144 questions built on them — including the paired traps on near-identical signs.
Browse all 208 grouped the way Japan groups them — regulatory, auxiliary plates, warning, indication, guide — and search by name or by sign number. Any selection turns into a deck of flashcards: sign shown, name hidden, tap to reveal.
Missed questions queue themselves automatically. Saved is the manual counterpart, for the ones you got right and still did not understand — put them on the shelf and study it in one go.
The home screen reads out how ready you are for the exam you are taking and names the one topic holding it back, with a way straight into it. It is an estimate of preparation, and says so — never a prediction of passing.
No server, no analytics, no ads, no tracking — the App Privacy label reads Data Not Collected. Everything is unlocked from the first launch, and the whole thing is localised into 12 languages, interface and question content alike.
Why it exists
Generating question variants is easy. Keeping each one faithful to what the rulebook actually says is the slow part.
On iPhone
One question, in full
This sign designates the minimum speed for motor vehicles — you must not drive slower than the number shown.
True
Sign 324 sets the minimum speed for motor vehicles. It is distinguished from the maximum speed sign (323) by an underline beneath the number.
“Designation of the minimum speed for motor vehicles.”
教則 付表3（1）26（規制標識）49th revision · 13 November 2024
By the numbers
How it’s built
Most of the work went into the content pipeline rather than the app. Generating question variants is easy; keeping each one faithful to what the rulebook actually says is the slow part. Every item carries its Japanese source text, a translation, the rule it comes from, the chapter reference, and the category of mistake it is meant to catch — and the whole bank is re-verified against the pinned 教則 corpus whenever the rules move.
Study runs in batches — ten by default, or five, twenty-five or fifty: new material first, then what you got wrong, then your weakest topics. Mastery means answered right first time, or twice in a row after a miss. There is no spaced repetition, deliberately — the case here isn’t “learn this for years”, it’s “pass on a date”.
On the App Store now, free. The code is cross-platform and the Android build is signed, but iOS is the only release so far. If a question looks wrong, the citation under it is there to check against — and I’d like to hear about it.
教則
The National Police Agency’s official rulebook for drivers — the document the examiners write the questions from, rather than a study guide about it.
外免切替
The procedure for converting a foreign driving licence to a Japanese one. It now includes the written check this app is built for.
Pinned corpus
Traffic rules change, so the bank is verified against one fixed revision of the rulebook rather than against whatever is current. When that revision is superseded, the mismatch is visible instead of silent.
Gokaku is an independent, unofficial study aid. It is not affiliated with, endorsed by, or connected to the National Police Agency (警察庁), the Ministry of Land, Infrastructure, Transport and Tourism (国土交通省), any prefectural police licence centre, or any driving school. Passing a mock exam in this app does not guarantee passing the official test. Traffic rules change — always confirm current requirements with your prefectural licence centre.