Bocca and Sayoko arrives at a huge industrial region. Sayoko befriends a strange girl by the name of Coco. Coco tells Sayoko that she is involved in a theatrical play nearby. Bocca and Sayoko later meet up with a guy who offers Bocca a job as a security guard. And while Bocca faces a team of saboteurs of the delivery truck that he is protecting, Sayoko is taken prisoner by the guy, who reveals himself to be a member of the Monster Union. Bocca's bow is damaged during battle, but his Aibar machine provides him a more stronger bow. As the battle goes on, the saboteurs which includes Coco, realizes who Bocca is and stops the battle. They show Bocca the contents in the truck and brings him to see someone he knows.
「猿人湾」という工業地帯にやって来るボッカと小夜子は、工場長の”マサル”に、製品運搬の護衛を依頼される。
そして護衛を開始したボッカの前に四人の少年少女「武装演劇集団・チェンタウロ」が現れる。
