Seppuku to prefer Chinese readings in official announcements, only the term seppuku was ever used in writing. So hara-kiri is a spoken term, but only to commoners and seppuku a written term, but spoken amongst higher classes for the same act. The practice of performing seppuku at the death of one's master, known as oibara (追腹 or 追い腹, the kun'yomi or Japanese reading) or tsuifuku (追腹, the on'yomi or Chinese reading), follows a similar ritual. The word means "suicide" in Japanese. The modern word for suicide is . In some popular western texts, such as martial arts magazines, the term is
Samurai Warriors 4 , a social spin-off game released on April 22, 2014 for the mobile phones also to commemorate the series' 10th anniversary. Koei Tecmo also collaborated with the Japanese Racing Association (JRA) to release on May 25, 2014 for the PC. "Derby Musou" reuses assets from "Samurai Warriors 4" to create a horse racing game, like that of the "Winning Post" series, with famous Japanese racehorses. Eight characters from "Samurai Warriors 4" make up the playable cast, plus Matthew C. Perry (known in-game as just Perry). The game received a revision, titled , which was released in Japan on February 11,