# Otsu-4 Anki Club: Kiken-butsu — Japan hazmat Class 4 exam prep

> Japan hazmat Class 4 exam prep (iPhone/iPad app by 丽佳 施.)

- Source: https://appshunter.io/ios/app/otsu-4-anki-club-kiken-butsu/id6797277373 (this page in markdown: same URL + `.md`)
- Developer: [丽佳 施](https://appshunter.io/developer/1894580777)
- Category: Lifestyle
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 7 MB
- Languages: American English, Japanese, Chinese (Simplified, China)
- Released: 2026-08-07
- Data updated: 2026-08-12
- User reviews in markdown: https://appshunter.io/ios/app/otsu-4-anki-club-kiken-butsu/id6797277373/reviews.md

## What is Otsu?

The Otsu-4 (乙4) hazardous-materials handler exam trainer for Japan — the license that raises hourly wages at gas stations and warehouses across Japan.

• 911 original drill questions with explanations (regulations / physics & chemistry / properties & firefighting) — real count, no inflated numbers
• 26 original Japanese mnemonics (goro) for designated quantities and key facts
• Full-format mock exam: 35 questions, 2-hour timer, graded with the real rule — 60% or better in every subject
• Leitner spaced repetition brings back exactly what you were about to forget
• Reference table of 30 Class-4 substances: quantities, flash points, solubility, extinguishing agents
• Study features work fully offline, including in airplane mode — no account or internet needed to learn

A banner appears at the bottom of the screen, and a full-screen ad may appear at natural breaks. An optional one-time "Remove Ads" purchase hides both.

Note: exam content is in Japanese (the exam itself is administered in Japanese). Original study material, not a copy of any commercial past-question book. Interface available in English, Japanese and Simplified Chinese.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Remove Ads | $0.99 | one-time |



## Version history (last 2 releases)

### 1.0.1 — 2026-08-08

Fixed internal ad configuration and improved overall stability.

### 1.0 — 2026-08-07

No release notes.

## More apps by 丽佳 施

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- [童童的萌宠面包房·小学数学口算](https://appshunter.io/ios/app/id6769093315)
- [Stack Tower Up](https://appshunter.io/ios/app/stack-tower-up/id6769321760)
- [Pomotown - Focus Timer](https://appshunter.io/ios/app/pomotown-focus-timer/id6769728830)
- [Lensage: Astro & Photo Planner](https://appshunter.io/ios/app/lensage-astro-and-photo-planner/id6769730141)
- [Ember — Private Diary](https://appshunter.io/ios/app/ember-private-diary/id6769777961)

All apps by 丽佳 施: https://appshunter.io/developer/1894580777

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-12.*