9.1.0-20J
The Japan-only 9.1.0-20J system update was released on October 10(11 in Japan), 2014.
Change-log
See here for the Japanese changelog. Among other things, this added theme support to the JPN Home Menu.
System Titles
The following titles were updated: Home Menu and CVer.
New3DS application title 000400102002CA00 was re-added as title-version v0, originally this title was added with the Oct 2 JPN-only update however apparently that title got removed then added again.
See Also
System update reports: