Raizel, protector of the nobles, along with his loyal butler Frankenstein and former Union experiment M-21, continue to spend their days at Ye Ran High School while keeping their true identities secret. They were living their lives as normal until one day, when a violent gang barges onto the school grounds. M-21 is forced to make a choice in order to protect the students. Meanwhile, DA-5, a mysterious special forces team, is dispatched to Japan on an investigative mission. What will become of the trio's peaceful new life?

Two nobles, Regis and Seira, arrive at Ye Ran High School as part of their investigation into a series of incidents in Japan. Raizel and Frankenstein conceal their identities when they interact with the duo, but Regis and Seira realize that M-21 is a modified human and grow wary of him. Meanwhile, Tashiro is caught up in another fight with street punks on his way home from school...

Seira realizes Regis is in danger and rushes to help him. Raizel and Frankenstein suspect that Tashiro and Kase might be in trouble as well, so they follow Seira. M-21 comes up with a plan to sacrifice himself to save all of them, and Regis confronts the danger by his side. The battle against DA-5 has begun! But they're up against the Union's state-of-the-art special forces team, an opponent that won't go down easily...