# Phone Guardian: Left-Behind — Alert the moment you leave it

> Apple Watch app alerts you when you leave your iPhone behind. (iPhone/iPad app by KAZUTO MATSUBARA.)

- Source: https://appshunter.io/ios/app/phone-guardian-left-behind/id6789723496 (this page in markdown: same URL + `.md`)
- Developer: [KAZUTO MATSUBARA](https://appshunter.io/developer/6789723498)
- Category: Utilities, Lifestyle
- Price: $1.99
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English, Japanese
- Released: 2026-07-15
- Data updated: 2026-09-03
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/phone-guardian-left-behind/id6789723496/reviews.md

## What is Phone Guardian?

"Wait — where's my phone?" Let's make that heart-drop moment a thing of the past.

Phone Guardian buzzes your Apple Watch the instant the Bluetooth link to your iPhone breaks. Find My helps you locate a phone after it's lost — Phone Guardian tells you the second you leave it, so you can just turn around.

■ Perfect for moments like these
- Heading out: know the second you leave your phone at the door
- Cafés & restaurants: never leave it on the table when you get up
- Travel & trips: avoid leaving it at hotels or airports
- Trains & buses: get alerted the moment you leave it on your seat

■ Key features
- Instant left-behind alert: your Watch buzzes within seconds
- Distance warning: a gentle heads-up before the connection is even lost
- False-alarm guard: a brief blip won't trigger it (0–10s grace)
- Safe Zones: silence alerts at home or any place you choose
- Ring your iPhone: find it loudly from your Watch, even in silent mode
- Also a watch face: turn the monitoring screen into a digital or analog clock, with your own photo background, world clock, and corner widgets
- Japanese / English: switch anytime inside the app

■ Battery friendly
Only low-energy Bluetooth and near-zero-power geofencing. No constant GPS — battery impact is minimal.

■ Privacy
No location, no analytics, nothing leaves your device. Everything stays local.

■ Before you start
- Requires an iPhone on iOS 17+ paired with an Apple Watch on watchOS 9+
- One-time purchase. No subscription, no ads.
- Due to watchOS rules, alerts can be delayed on some models or usage patterns. If that happens, keeping Phone Guardian as your Watch face is the most reliable setup — and it doubles as your everyday clock.

Keep your iPhone safe, right there on your wrist.

## Key features

- Instant left-behind alerts
- Distance warning
- False-alarm guard
- Safe Zones
- Ring iPhone from Watch
- Watch face functionality
- Battery friendly design

## Recent user reviews (4 of 4)

All indexed reviews: https://appshunter.io/ios/app/phone-guardian-left-behind/id6789723496/reviews.md

### 5/5 — 最初だけだった

*2026-09-02*

2026年7月後半に入れて、半月位は頼もしかったが、最近全く作動しない。今日iPhone忘れて出掛けてしまった😭

↑コメント入れたら直ちにバグ取りしていただいた様でありがとうございます。今のところ調子良いです。

**Developer response:** 本日アプリのバグを修正しました。
こちらも気付かないバグがあった為、ご指摘いただきありがとうございます。
アップデートし引き続きご利用よろしくお願いします！

### 2/5 — コンプリケーションが欲しい

*2026-08-29*

普段使う文字盤のコンプリケーションとして、動作状況を確認できるコンプリケーションが欲しい。

**Developer response:** 普段使用している文字盤のままでも振動通知を受け取ることができます。
動作確認のコンプリケーションも今後のアップデートで検討させていただきます。
ご意見ありがとうございます！

### 4/5 — これなら私でも忘れない

*2026-08-19*

時計を身につけて朝出勤する時などに忘れないのは大きいと思いました。
頻繁に忘れることはないけどいつか起こることを未然に防げるのは良いですね。

スマホから離れると振動が発生するので余程のことがない限り気づかない状況にはならないと思います。

**Developer response:** 嬉しいコメントありがとうございます！
朝のスマホ忘れも実感していただけますが、忘れた頃に街中で突然感じる日が来ると思います。
あの瞬間、（あ、スマホ！）と助けられる日が来れば幸いです☺️
引き続きご利用、よろしくお願いいたします✨

### 1/5 — 期待外れだった

*2026-08-18*

テストでやってみたときすぐ通知がきてよかったですが、普段使う分にはApple Watchでアプリを常時文字盤として開いていないと見守り終了してしまい、使えません。

**Developer response:** 先日バグが見つかりましたが、修復完了しました。
また、Watch側のアプリを常時開いていなくても、通常の文字盤でも振動の通知を受け取れます。
お気に入りの画面で、安心してお楽しみ下さい。
今回のご指摘いただき本当にありがとうございます。
バグに気付くきっかけになり、」助かりました！

## Frequently asked questions about Phone Guardian

### What devices does Phone Guardian support?

Phone Guardian requires an iPhone running iOS 17 or later, paired with an Apple Watch running watchOS 9 or later. It is designed for both iPhone and Apple Watch.

### How much does Phone Guardian cost?

Phone Guardian is a one-time purchase priced at $1.99. There are no subscriptions or ads associated with the app.

### Does Phone Guardian have ads?

No, Phone Guardian is completely ad-free. The app is a one-time purchase and does not contain any advertisements.

### How often is Phone Guardian updated?

The latest version of Phone Guardian is 1.1, last updated on July 27, 2026. Update frequency is not explicitly stated but indicates ongoing development.

### What is the age rating for Phone Guardian?

Phone Guardian has an age rating of 4+. This indicates it is suitable for users of all ages, with no mature content.

### Can Phone Guardian alert me if I leave my phone in a specific location?

Yes, Phone Guardian features 'Safe Zones' which allow you to silence alerts at home or any other chosen location, preventing false alarms in familiar places.

### How does Phone Guardian handle potential false alarms?

The app includes a 'False-alarm guard' feature with a grace period of 0-10 seconds. This prevents brief connection blips from triggering an alert.

### What happens if alerts are delayed on my Apple Watch?

Due to watchOS rules, alerts can sometimes be delayed on certain models or usage patterns. For the most reliable setup, keeping Phone Guardian as your Watch face is recommended, as it also functions as a clock.

## Version history (last 3 releases)

### 1.2 — 2026-08-31

[Important Bug Fix]
Fixed an issue where notifications could occasionally stop working after adding or removing a Safe Zone.

[Apple Watch]
Notifications can be received by vibration even when the MamoruKun app is not displayed on Apple Watch. You can continue using your favorite watch face as usual.

### 1.1 — 2026-07-27

- Added smaller Safe Zone radius options (10m/30m/50m) for tighter spaces
- Fixed a bug where the watch face background photo didn't update after changing it in Settings

### 1.0 — 2026-07-15

No release notes.

## More apps by KAZUTO MATSUBARA

- [Ninja Shogi: AI Board Game](https://appshunter.io/ios/app/ninja-shogi-ai-board-game/id6793572266)

All apps by KAZUTO MATSUBARA: https://appshunter.io/developer/6789723498

## Related topics

[phone guardian](https://appshunter.io/ios/topics/phone-guardian) · [don't forget your phone](https://appshunter.io/ios/topics/don-t-forget-your-phone)

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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 2026-09-03.*