This movie starts with Saze X playing basketball. Suddenly, a lightning bolt hit the earth. They walked towards it and found a boy. The boy's name is Ricky, and he thinks he has forgotten everything. On the other hand, Remy told Sazer-X that a giant monster named Mechanical Giant Bulgario had approached Earth and was destroying buildings. Sazer X still defeated the monster. But then something flashed into their eyes, and Takuto mistook it for a cosmic capsule. In fact, this is the Bosquito people that exist within Bulgaria, which Professor Horiguchi later explained.
一年夏天,一个名叫武川优希的6岁女孩来到祖父家度假,闯入了传说中充满怪物的山神森林。就在她极度担心迷路的时候,一个戴着狐狸面具的大男孩出现在她面前,带领萤火虫找到了回家的路。尽管萤火虫非常感激,但男孩禁止她触摸自己的身体。