Japan’s post-apocalyptic wasteland replete with dust can only be saved by one thing—fungus. Bisco Akaboshi, a wanted criminal and skilled archer, searches for a legendary mushroom, known as Sabikui, said to devour any and all rust. Joining him on this epic saga to save the country is a giant crab and a young doctor. Can this unlikely trio find the fabled fungi and save the land?

高中三年级的冬天。高中生活剩下的时间已经不多。这样下去总有一天会迎来毕业，任谁都是这么想的。
直到他的突然归来。
初中时一度搬迁到遥远城市的同级生。与不合时节的转学生的重逢，在他们想着“总有一天”会迎来结束的心情当中，鸣响了一声小小的起跑信号……