Its central characters are a vampire girl named Miyu and her demonic companion Larva. Miyu is the daughter of both a human and a shinma (demon) and as such she was awakened as the guardian whose destiny is to hunt down all stray shinma and send them back to the darkness.

因战争连年，地球环境遭到破坏以致频临灭亡，人类被迫离开地球，五百年来一直生活在巨大太空船内的城市中；主控城市的电脑系统为免人类重蹈覆辙，特意隐瞒实情，让人类生活在虚拟二十世纪的社会中。飙车族矢作省吾从不关心社会及世界事物；他与同伴每天都在玩乐及飙车。直至有一天，他的一位旧朋友把一部神秘的超级电单车留了给他。这部名叫格兰度的超级电单车原来隐藏着一个重大的秘密。利用这部电单车，省吾发现了人类原来一直生活在巨大的太空船内，由一部名叫巴哈姆的超级电脑系统操控着…