# Gengou Lib — Japanese-Christian Years

> Converts Japanese era names to Christian years and vice versa. (iPhone/iPad app by Masayuki Akamatsu.)

- Source: https://appshunter.io/ios/app/gengou-lib/id284830543 (this page in markdown: same URL + `.md`)
- Developer: [Masayuki Akamatsu](https://appshunter.io/developer/284722836)
- Category: Productivity, Utilities
- Price: Free
- Rating: 2.50/5 from 2 App Store ratings · 58 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 6 MB
- Languages: American English, Japanese
- Released: 2019-02-12
- Data updated: 2026-08-13
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/gengou-lib/id284830543/reviews.md

## What is Gengou Lib?

"Gengou Lib." is a quick reference of the Japanese era system. This application has functions as below.

- Era and Year Search
- Period picker
- Era picker
- Christian era year picker
- Japanese era year picker
- Show this year button 
- Texts can be shown in Japanese or English independently of the default language setting.
- Application badge can show this year number in the Japanese era or the Christian era.

The Japanese era system identifies a year by the combination of the era name (Gengou or Nengou) and the year number within the era. For example, A.D. 2001 is Heisei 13. Please note that two Gengou schemes were used in Parallel from 1331 to 1392 during Nanboku-chō period. 

This application would be very useful if you are working with the governments, municipal offices and/or certain companies in Japan.

## Key features

- Era and year search
- Period picker
- Era picker
- Christian era year picker
- Japanese era year picker
- Show this year button
- Multi-language text display

## Recent user reviews (10 of 58)

All indexed reviews: https://appshunter.io/ios/app/gengou-lib/id284830543/reviews.md

### 4/5 — 巳年が「己年」になっている

*2022-01-20*

今まで誰も誤字に気付かなかったのでしょうか。
とても便利なアプリですが、誤字のため星一つ減。

### 5/5 — 簡単操作

*2019-07-25*

操作が簡単かつ単純で分かりやすいです。「何年だったかな？」という疑問をサクッとすぐ調べられます。シンプルですぐ使えます

### 5/5 — Very useful

*2015-10-02*

Very useful app for Japanese who lives outside of Japan. Thanks to the developer

### 4/5 — いいです！

*2013-10-02*

シンプルで使い易いです。各元号から入ってゆけるので重宝しています。

### 4/5 — シンプルで広告もない

*2012-12-11*

広告が無いので気に入りました。iPhone 5の大きさに対応してくれればいいかなと思う

### 4/5 — 確かにお勧めの一品ですね。

*2011-09-05*

ダウンロードした事を忘れちゃう、そんなアプリ。(悪い意味じゃない)。

### 3/5 — 要望

*2010-02-20*

十二支表示もあると、より便利になると思います。

### 4/5 — Interesting

*2010-02-02*

My wife and are always trying to figure out dates in Emperor years, so this is helpful. 

Don't think that the current emperor is going to make it until the year 2100 though.

### 5/5 — わかりやすい

*2009-11-13*

Does what it says it does; matches years from the Western calendar to those of the Japanese. I can't imagine ever having to buy the full version... all the functions are here in this free one!

### 3/5 — 要望

*2009-10-31*

便利なんだけど、明治以前とかの実用性の無いアップデートより現状＋年齢がわかるようにしてほしいですね。
今のシンプルなままで西暦or元号の入力（デフォルトで数字入力、これはできるかはわかりませんが；）と年齢表示がされれば即買いします！

## Frequently asked questions about Gengou Lib

### How does Gengou Lib help with Japanese era names?

Gengou Lib provides a quick reference for the Japanese era system, allowing you to search for eras and years, pick specific periods, and convert between Japanese and Christian era years. It can also display the current year in either system.

### Can I use Gengou Lib in English?

Yes, the texts within Gengou Lib can be displayed in either Japanese or English, independently of your device's default language setting. This makes it accessible for users who prefer English.

### What devices does Gengou Lib support?

Gengou Lib is available for iPhone, iPad, and iPod touch devices. It is designed to function across these Apple platforms.

### How often is Gengou Lib updated?

The latest version of Gengou Lib is 3.0.0, and it was last updated on August 26, 2025. This indicates a recent update, suggesting ongoing support and potential improvements.

### What is the age rating for Gengou Lib?

Gengou Lib has an age rating of 4+. This means it is considered suitable for children aged 4 and above, with no mature content.

### Is Gengou Lib free to use?

Yes, Gengou Lib is available for free. There are no costs associated with downloading or using its core features.

### What is the user sentiment for Gengou Lib?

Gengou Lib has a rating of 2.5 stars from 2 ratings. This suggests a mixed to negative user reception based on the limited feedback available.

### Does Gengou Lib handle historical Japanese era overlaps?

The application notes that two Gengou schemes were used in parallel from 1331 to 1392 during the Nanboku-chō period. This indicates an awareness of historical complexities within the Japanese era system.

## Version history (last 5 releases)

### 3.0.1 — 2026-07-04

Minor bugs have been fixed.

### 3.0.0 — 2025-08-26

■ Quick Search for Japanese Eras
  Find any era instantly! Search by hiragana (しょうわ),
  romaji (showa), or kanji (昭和) - all input methods work!
  Supports partial matching and year-based search.

■ Dark Mode Support
  Easy on the eyes for comfortable nighttime use.

■ Other Improvements
  Enhanced search performance and bug fixes.

### 2.1.0 — 2019-04-12

Supports the new era "令和 (Reiwa)"
Source: "初春令月氣淑風和" from Man'yōshū
Reference: "仲春令月時和気清" from Wen Xuan

### 1.0.1 — 2012-03-02

- Fixed a bug on the Japanese Calendar in the Settings.

### 1.0 — 2008-07-06

No release notes.

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| [Japanese Era Converter (JEras)](https://appshunter.io/ios/app/japanese-era-converter-jeras/id1559193412) | — | Free | Productivity |
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## More apps by Masayuki Akamatsu

- [Yes\|No Free](https://appshunter.io/ios/app/yesno-free/id284722833)
- [Alarm Free](https://appshunter.io/ios/app/alarm-free/id284728433)
- [Compass Free](https://appshunter.io/ios/app/compass-free/id284735786)
- [picocalc](https://appshunter.io/ios/app/picocalc/id284740333)
- [T4Two](https://appshunter.io/ios/app/t4two/id284910005)

All apps by Masayuki Akamatsu: https://appshunter.io/developer/284722836

## Related topics

[gengou lib](https://appshunter.io/ios/topics/gengou-lib) · [gengou](https://appshunter.io/ios/topics/gengou) · [iyua yakobu](https://appshunter.io/ios/topics/iyua-yakobu)

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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 2026-08-13.*