Narumi Katou is a middle-aged man who suffers from the bizarre ZONAPHA Syndrome: a rare and inexplicable disease that causes its victims to endure severe seizures at random, with the only cure being to watch someone laugh. One day, during Narumi's part time job, a young boy with a giant suitcase fleeing from three adults runs into him. The boy introduces himself as Masaru Saiga, the new owner of the famous Saiga Ente...