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...

M-21 finds himself suddenly blending in easily with normal life. He's even begun to develop some degree of mutual trust with Regis, even though the two of them initially clashed over every little thing. Tao tries to hack into the police department's security system, but Kase intercepts him, and an unexpected hacking war breaks out. Meanwhile, the Union's special forces team, DA-5, finally tracks down M-21's location...

The Union's special forces team, DA-5, has captured M-21, but he sees this as a chance to search for information on his old comrades. When things don't go as he had expected with M-21, Shark begins to search for a new target... Meanwhile, Tashiro and Seira encounter Takio on the street and notice he's in trouble, and Kase is surprised to find himself hitting it off with Tao, the one he'd gotten into a hacking battle with.

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...

Frankenstein's battle with Takio and Seira's battle with Hammer grow more intense. Tao and Takio clash as Tao tries to keep Tashiro and Kase out of the conflict, but their leader, Crans, enacts an unbelievably brutal plan in order to win... Meanwhile, Raizel reaches M-21 and uses his overwhelming power to take on Crans.

Tashiro finds himself increasingly attracted to Seira, so he asks the other guys for advice. Unfortunately for him, the likes of M-21, Tao, and Takio are already a hit with the ladies, so their advice isn't very helpful, and Frankenstein only gives him boastful stories from his own history. Will Tashiro's plan to get his feelings across to Seira be successful?

Since contact with Regis and Seira has been lost, Regis's grandfather, Gejutel, heads to Japan on Raskreia's orders. Once he arrives there, he unexpectedly runs into Frankenstein and Raizel. Who were the Frankenstein and Raizel that Gejutel knew in the past? Are their true identities finally about to be revealed?

Raizel and Frankenstein first met in Lukedonia, the country of nobles. Raizel took Frankenstein, who was a noble hunter at the time, into his mansion to work as his butler. Frankenstein protected him for several years, but then some among the nobility who had unfavorable opinions of the duo began to revolt. What decision did Frankenstein and Raizel reach in response to this conflict?