From an article in Publishing Perspectives by Robin Birtle:
In 2011, the only significant e-book revenue in Japan was derived from manga comics. To develop as a mainstream market, a significant push was, and still is, needed from one of the handful of industry players with real clout. One of those players, Rakuten, announced in November 2011 their intention to purchase Kobo. That Kobo will be able to launch a Japanese service on July 19th this year is a truly impressive feat of rapid execution. Pre-orders for the Kobo Touch commenced on Monday with a price set at ¥7,980 ($100), well under the psychologically important ichiman-en (¥10,000) mark.
There is little doubt that Kobo and Rakuten between them will do more in the next 12 months to push the Japanese e-book market into the mainstream than the industry establishment has managed in the last 10 years. But two of the other potential factors from 2011 are also worthy of mention.
First, Sony takes the prize for “Squandering a Leading Market Position.” For a couple of years Sony has been the go-to vendor for Japanese consumers interested in a dedicated reader, and its e-book store is perfectly serviceable if not ground-breaking. Sony, though, does little to market their service, has not launched reader apps for mobile devices and has maintained device prices at a level that screams ‘niche’ to potential buyers. ($250 for an entry level Wi-Fi enabled reader? Per-lease). Sony can comfort themselves with their position as technology provider to Pottermore but unless they radically shake up their approach they will be irrelevant in the Japanese e-book market ex-Potter within two years.
Much more in the article.