|Occupation||Tokyo Police Fifth Officer|
|Manga Debut||Act 219|
Shin'ichi Kosaburō is a fifth officer with the Tokyo Police Department. After Kujiranami Hyōgo escaped from his cell and began rampaging with a grenade launcher, Shin'ichi - like his compatriots - is at a loss for how to deal with the disaster until Myōjin Yahiko intervenes with a plan and the courage necessary to win. Though frightened, Shin'ichi gives front line support to Yahiko and rallies the other officers to help subdue the behemoth.
Inspired by Yahiko's courage and skill, Shin'ichi is the only one to notice the young swordsman's display of Kenki and, when it seems that Kujiranami's strength has finally overwhelmed the boy, Shin'ichi begs heaven to spare the life of such a potentialed youth - whose skills he believes will someday be of great use to the Japanese people. The young rookie officer's prayers are answered when Himura Kenshin appears on the scene to rescue his friend and bring down the mad samurai. Shin'ichi later gives an official police report of Kenshin's arrival which describes the rurouni's demeanor as "majestic" and compares his attack to a bolt of lightning.