Takashi is just a regular fifth grader when a new student, Taro Tanaka, appears. Later Takashi realizes that Taro is an alien and tries to find out more about him. He has many adventures with Taro. Takashi soon gets into much trouble and starts to have a bad reputation because of Taro such as giving his childhood friend Kyoko an explosive bomb for her birthday (which Taro had switched with a Taro doll Takashi had meant to give Kyoko).