Rurouni Kenshin

Rurouni Kenshin is a manga and anime series that takes place in the early Meiji era. The series follows the titular character Himura Kenshin, a former assassin known as Hitokiri Battousai who has given up killing, as he seeks redemption through the protection of innocents. The series is also responsible for the concept of a sakabato, a katana with the blade on the wrong edge, and a rurouni, a traveling swordsman.

Fanfiction
The Rurouni Kenshin fandom has a very large percentage of AU fic. These stories range from modern-day fics to generic-fantasy fics, with everything in between.