Mishima Ei'ichirō is the older brother of Mishima Eiji and an agent of the police force under the command of Lt. Fujita Gorō. Born and raised in Shingetsu Village - a small town which has been taken over by Shishio Makoto and ruled by Shishio's henchman Senkaku - Ei'ichirō is ordered to sneak back into the populace in order to relay information regarding Shishio's actions back to the police. However, after catching wind of the Meiji Government's plans to abandon the village to Shishio's machinations, Ei'ichirō desperately attempts to smuggle his parents and younger brother out of Shingetsu to safety. Unfortunately, his escape plot is discovered and, fatally wounded by Senkaku, Ei'ichirō is only able to flee with Eiji into the forest before succumbing to his injuries. He is discovered by Himura Kenshin and Makimachi Misao and, with his dying breath, begs the two to save his little brother and his hometown.