Shinji Obara

Fuu, a waitress who works in a teahouse, rescues two master swordsmen, Mugen and Jin, from their execution to help her find the "samurai who smells of sunflowers." (imdb)

Makuhara city has been off-limits since it was reported that a severe earthquake hit. Two high school boys, Yamato and Takeru meet and hit it off while they bicycle to Makuhara from differing points, each with their own purpose. They sneak into Makuhara and are surprised by the heavy guard around it. Makuhara has changed into a confused place where all the adults have died mysteriously, and only boys and girls under around 20 years old survive (IMDB &me).