Crescent Moon in the Warring States (戦国の三日月 Sengoku no Mikazuki) is a one shot story and first debut of Rurouni Kenshin author Nobuhiko Watsuki.
It tells of the tale of the first Hiko Seijūrō of the Hiten Mitsurugi-ryū and his ally Isshinta, who are of the domain of Kitakata in the Sengoku period of Japan, pitted against the larger and belligerent domain of Nagumo. At war with seemingly insurmountable odds, Hiko and Isshinta fight not just for themselves, but to those that await for them and hope for their safety off of the battlefield: the princess of the Kitakata lands and Isshinta's girlfriend, both named Natsu.
Created as his first independent work, Nobuhiko originally envisioned Crescent Moon in the Warring States as a fantasy story with an Eastern/Northern European inspired setting, but upon seeing that the manga market in the 90's was already filled with fantasy set stories, he instead set the story in the Sengoku period of Muromachi Japan. The main character in mind was not that of Hiko Seijūrō, but that of Isshinta, which he wanted to tell a story in where kindness turns into courage and the growth of a "weaker character" who finds that courage.