"My phone addiction was too bad, so I just built an app": a TikTok account with 42 followers sent a phone-quitting app to the Japan bestseller charts in one week

もちのう (Mochinou, "mochi brain"), by Japanese indie developer Yu Mitsuda, is a phone lock app that you can't undo yourself, paired with a mochi-brain mascot that gets weaker the more you scroll. It launched in July and got little attention. In mid-October the developer opened a persona account and posted 10 TikToks in one week. The app squeezed into the Japan App Store Productivity Top Grossing chart, peaking at #46 in 10-31. The features are common. What it did right: a very cheap content playbook, and a low-bar chart. When TikTok stopped, it started falling. Below: how it rose, where the money came from, why it couldn't hold, and what you can take from it.

A 23K-view "I built an app" post

At 8:50 AM on Oct 18, 2026, the TikTok account @sumaho_misugi0 (「スマホみすぎ」, roughly "too much phone") posted a video with the caption: 「スマホやめたい時に限って手が勝手に開いちゃうので、自分でも解除できないアプリ作りました‼️」 — "Right when I want to quit my phone, my hand opens it on its own, so I built an app I can't unlock myself!!" The closing line reads 「App Storeで「もちのう」って入れたら出てきます🔍」 — "Search 「もちのう」 in the App Store and you'll find it."

That post later reached 23,645 views and 628 likes. The next evening they posted again: "自分でも解除できないアプリ「もちのう」、App Storeのランキングに載りました‼️" (The app I can't unlock, "もちのう", made the App Store ranking, thank you all). That post got 17,965 views.

The same day, a two-star App Store review appeared: "TikTokでみつけていいじゃんって思ってインストールしました" (I saw it on TikTok, thought it looked good, and installed it), followed by a complaint that "the moment the tutorial ends you hit the paywall." From that day on, reviews came in almost daily. Before that there were two or three in July, one in August, and none in September.

By 11-06 the account had only 42 followers and 3,229 total likes. From 10-16 to 10-22 it posted 10 videos in total, about 61K views combined, then stopped.

What it is

A phone-quitting iOS app, Japan store only, Japanese only. The store description explains up front how it differs from system features: "The iPhone's built-in Screen Time can be opened by tapping 'Ignore Limit'. That escape doesn't work on the night you most want to open it." Its "がっつりモード" (hardcore mode) can't be undone even by you until the timer ends, and it blocks the delete-the-app escape route too.

The other half is emotional design. The website mochinou.vercel.app first makes you pretend to scroll short videos, then shows three numbers: 4.7 hours a day, 96 unconscious app opens, and "7 years gone from your life". Then a mochi-brain mascot appears: "替你融化的脑子,もちのう" (the brain that melts for you, もちのう). The more screen time, the weaker it gets; the longer you stay off your phone, the more energetic it becomes. An October update added "leave the app and raise a fish tank".

Its target audience is clear: the description says "studying for exams, want to focus", the TikTok copy reads "you open TikTok right before the exam", and the tags are #jk (high school girls), #大学生 (college students), #勉強垢 (study accounts).

What exactly the TikTok playbook is

The captions of the 10 videos follow almost one template, split into four parts:

• I'm that patient. "スクリーンタイムやばすぎてアプリ作っちゃいました" (my screen time is so bad I built an app), "自称ドパガキ女です" (self-described dopamine-brat girl). "ドパガキ" is a meme among Japanese young people for 2026 years, referring to people ruined by short video.
• Tell people to search the store for the name, not click a link. Every post ends with the same line: "Search 'もちのう' on the App Store." Concentrated search volume is also likely helping push the name and keywords up (inferred).
• Viral moments become content. When 10-19 hit the charts and 10-20 ranked #65 in productivity, that social proof turned straight into the next video.
• Comment-section doubts become topics. Someone commented "Just delete the app then," so 10-19 posted at dawn: "You can't delete the app while it's locked."

One more detail: the persona doesn't hold together. The first post says they're a college student, later they tag #jk and call themselves a "dopamine-addicted girl." Over four months the same developer account shipped 5 apps (calorie counting by photo, relationship repair, anti-oversleep alarms, and more). A second TikTok account, @m3_yorusumaho, promoted もちのう under a July name, then renamed itself and pushed the same developer's alarm and calorie apps, 200 posts in total, mostly tens to over a thousand views. This is someone who mass-produces apps, mass-creates accounts, and promotes whichever one takes off. A user comment says they came from YouTube Shorts, so July tried other accounts too; they just never gained traction.

Where the money comes from

Free to download, but the free version only lets you lock 1 times a day, for 10 minutes each. The onboarding first shows you how much of your day you've "melted" away, then drops a paywall straight in, the same playbook as Opal, the top US product.

Store listing prices: yearly ¥4,000, weekly ¥480. The official site says "¥3,980/year (¥11 a day) · 3 days free." The third-party site APPLION lists 11 in-app tiers: yearly at ¥6,000 and ¥4,000, a "75% off" tier at ¥1,000, a "half price + 7 days free" tier at ¥2,000, plus a one-time purchase at ¥10,000 and a special offer at ¥5,800. This many tiers suggests price testing, along with discount retention offers when the paywall is dismissed (inferred).

No public revenue figures. What's visible is the charts: it ranked #65 on Japan's productivity Top Grossing chart 10-28, #46 on 10-31, and #91 on 11-06, sitting alongside two VPNs and a similar app-blocker. Getting into the top 100 on this chart doesn't take much: a few hundred paying users, plus high-ticket weekly subscriptions and one-time purchases, is enough (inferred). In other words, it isn't selling a lot; this chart is just easy to crack.

User reactions to the price are consistent: "In-app purchases are too hard for kids" (11-01), "Without paying you only get 10 minutes, and it's expensive" (10-30), "Other than having to pay, it's great, just let me lock for two hours" (10-29). The target audience is students, who have limited ability to pay, which is one reason its ceiling is low.

Why it couldn't keep going

After 10-22, the TikTok account stopped posting. Over the next two weeks:

Data: App Store Japan store, 10-28 to 11-06. Total ratings rose from 341 to 425, average 4.5.

New installs came almost entirely from that wave of videos, with no word of mouth forming. Worse, the negative reviews all point to the same problem: it doesn't lock. "Set everything to blocked and more than half the apps still open" (10-28, one star), "The SNS blocks often lift on their own" (10-26), "I set it several times and the apps I wanted to block still worked" (11-04), "I paid but it only shows the free version" (11-04), and one that says outright, "Too similar to Opal, and Opal lets you use more for free" (10-25). An app whose core promise is "truly locked" that doesn't lock will struggle to retain users.

Who it's competing with

The Japanese niche is crowded. There are 60+ Japan-store apps with "smartphone dependence" or "screen time" in the name, and half of them launched after 2026 June.

Functionally it has nothing new: forced locking (Blockin, スタロック, Opal) was already there, and the raising-a-character mechanic is "raising fish." It outperformed the other indie entries thanks to packaging (a cute character, a storytelling website) and that one week of content, not features. Few people know about it: no media coverage, nothing on X, no public revenue.

If it were you

One-line verdict: Don't build another blocking app for Japan. The market is already saturated, and もちのう itself only held on for a week. What's worth taking is the nearly zero-cost launch playbook: the developer appears as the "patient" in their own videos, posts 10 videos in a concentrated week, ends every one by telling viewers to search the app name in the store, and finds a country with a low barrier and a category Top Grossing chart, using high-ticket subscriptions to turn a small number of downloads into chart rankings.

Who it suits: One or two people who can ship a working iOS app in a week and are willing to post short videos daily, writing copy in the local language. Having a scenario you genuinely struggle with is even better (quitting phone use, waking early, expense tracking, study check-ins all fit), since the persona has to be believable.

Who it doesn't suit: Anyone wanting a long-term business (this playbook's growth stops the day the videos stop, so you have to keep posting); anyone who can't keep stability up (forced locking through the Screen Time API easily produces "doesn't lock" bugs, and negative reviews will wipe out the core promise); anyone aiming at the English-speaking blocking market (Opal, one sec and AppBlock already own it and are buying heavy ad traffic).

How to do it: Two ways to follow. One: switch countries. Students in Korea, Taiwan, and Southeast Asia face the same exam pressure, and few local-language "a lock you can't undo + cute character" apps exist yet (inferred; before starting, search the local App Store and check the top 100 on the productivity Top Grossing chart to gauge the bar). Two: do what it did badly. Make the "it actually locks" part solid, and offer students a low-price tier (say, pay per semester). Half its negative reviews are about not locking and half about price. Structure the paywall the same way: first show users how long they've been scrolling each day, then bring up the paywall, with 3 free days and a discount retention offer on close.

How to get installs: Run a persona account built on "I have this problem myself," and concentrate 8–10 posts into the launch week; end every post with the same line, "Search XXX on the App Store"; when the app charts, turn "it charted" into the next video; and answer the most common comment doubts with reply videos. Don't stop after a week the way it did. Schedule the video rhythm through the end of exam season.

When to start: East Asian exam season runs from December into the following February (in Japan, the January common exam and the December finals), and students trying to quit their phones are most likely to search then. Have the app and first batch of videos ready before early December.

Signs you're reading it wrong: ① None of your first 10 videos get past 5,000 views, meaning the persona doesn't land locally; ② videos get traction but store-search downloads don't push you into the top 100 on the sales chart, meaning that country's chart bar is higher than Japan's and the high-ticket model won't work; ③ new ratings and video views rise and fall together and drop back the moment posting stops, and negative reviews are mostly "doesn't lock," meaning you copied a one-off traffic spike without building a product people stick with; ④ Apple tightens the Screen Time API or the OS adds a way to dismiss the block with one tap, and the core promise is gone.

Data and sources

• App Store Japan store: productivity free chart, Top Grossing chart, rating counts, reviews (10-28 to 11-06); iTunes lookup id 6788616811 and the same developer's other apps.
• Listing and pricing: App Store page; APPLION (in-app purchase price table).
• Website: mochinou.vercel.app (11-06).
• TikTok: 10 posts from @sumaho_misugi0 (10-16 to 10-22, view counts as of 11-06), @m3_yorusumaho.
• Competitors: App Store Japan store ratings and productivity Top Grossing chart rankings, 11-06.
• The APPLION claim that it reached "#32 best on the productivity monthly chart (10-26)" is unverified. No public revenue figures exist, so every statement about revenue scale in this piece is inferred from the charts.