24 Kindle Books Earning ¥50,000–70,000 a Month in Royalties. Real Data From 16 Months and ¥750,000 of "Volume-Model" Self-Publishing

The Published Numbers

Period	Royalties (per month)
March 2021 (start)	¥5,000
April–May	¥10,000–14,000
June–August	¥36,000–52,000
From September	Stable at ¥50,000–67,000
January–July 2022	¥55,000–80,000
Cumulative (16 months)	Over ¥750,000

Books published: 24
Royalty rate: 70% (KDP Select)
Revenue sources: sales + Kindle Unlimited pages read (about ¥0.5/page)
The most recent title (15,000 characters, ¥480) earned about ¥6,000 in its first month

Business Overview

Starting with zero publishing experience, the author built a model of mass-producing short business/practical e-books (10,000–20,000 characters) on Kindle. Each title earns only about ¥2,000–3,000 a month, but 24 titles together produce ¥50,000–70,000 monthly. Kindle Unlimited’s per-page payouts form the revenue floor of the structure.

Lessons and Analysis

Kindle publishing is a game of “building a shelf,” not “hitting it big with one book.” Even though the average per-title revenue is tiny, volume creates reader circulation (readers pick up the author’s other books), and the backlist sells the new releases. The figure of 24 books = ¥60,000/month = ¥2,500 per title is an extremely practical planning unit for anyone starting out.

A rare side business that is complete inside platform marketing alone. With no blog or social media promotion, riding only Amazon search and Kindle Unlimited recommendations was enough to reach the ¥50,000s per month. This is the same “marketplace-type” acquisition as app store acquisition for apps — accessible even to people with no audience.

The constraints are low unit prices and platform dependence. The plateau at ¥50,000–70,000 a month stems from the price band (a few hundred yen) and the ceiling on readership. KDP’s terms and royalty rates holding the lifeline is the same structural risk as the low multiples in YouTube channel sales.

Inside the “24 Books” — the Practicalities of Volume Production

The unit economics of this model are clear-cut. One book of 10,000–20,000 characters — the equivalent of 5–10 blog posts — sells for around ¥480 and earns ¥2,000–3,000 a month. In other words, the labor of writing one book (a few weeks of side-project time) converts into a permanent stock of a few thousand yen per month. Twenty-four books is the integral of that.

The Kindle Unlimited per-page payout (about ¥0.5/page) as a revenue floor is also practically important. Readers who won’t clear the purchase hurdle (paying ¥480) will still read on the all-you-can-read plan. A book can earn by being read, not only by being bought — a mechanism that fits the volume model well.

The Value of a Visible Ceiling

The honesty of this case lies in recording stability, not growth. The plateau at ¥50,000–70,000 a month reveals a structural ceiling: (1) the price band’s upper limit (self-published practical books top out at a few hundred yen), (2) the ceiling on readership per title, (3) diminishing returns on backlist revenue as the catalog grows.

Paths through the ceiling are visible in other cases. The education app reaching ¥4.61 million a year got there by picking a market with large store search demand; the ceilings on paid note articles and online salons are set by unit price and the size of the loyal fanbase. Rather than pushing Kindle toward ¥200,000 a month, maintaining the ¥60,000/month Kindle shelf as a “finished asset” and building the next shelf (another platform, another theme) is likely the more rational extension of this model.