Saemonnosuke Ueshita is a samurai turned zombie who desperately tries to hide the fact that he is a zombie from the people around him. He lives in the home of 80-year-old Shokichi who fancies himself a modern Sherlock Holmes, but lacks stamina and concentration. When Saemonnosuke β on his way back home from grocery shopping β rescues the foul-mouthed girl Aoi from a group of zombies, Shokichi sees his chance to be a real private investigator and decides to help the girl. The three set out on a hilarious, action-packed journey to uncover the truth behind the zombie mafia and the whereabouts of the elusive 'zombie flower'.