【Carrying Lingering Regrets, the Ghost Taxi Runs Again Tonight】 In Tokyo, where the scars of World War III remain, Takumi Tatara works for a certain Taxi company. By day, he is a lowly Driver, but by night, together with his younger sister Karin who possesses the Taxi, he drives through the city as the Driver of "Zero-Bako," picking up Ghost guests with lingering Regrets.

One night, the siblings pick up the spirit of a mother holding her young son, wishing to go to her husband with whom she was supposed to celebrate a birthday. However, creeping up on that mother and child is a "Furei" (Rotten Spirit)—a supernatural phenomenon that haunts lingering regrets and rots the soul――? Carrying souls that have nowhere to go and delivering their remaining wishes, the siblings' Ghost Taxi Action begins.