Last of the Shin Kyuuseishu Densetsu pentalogy. A prequel set between Kenshiro's defeat at the hands of Shin and the beginning of the manga.

One normal school day, Rikka Takanashi notices Makoto Isshiki secretly passing a flash drive to Yuuta Togashi. Curious, Rikka talks to her friends about the case, who agree that Yuuta is hiding something from her. They decide to discover the contents of the flash drive by any means necessary, but to their surprise, it merely contained pictures of an idol that Yuuta adored back in middle school. However, Rikka takes offense, as she claims that this breaks their contract as lovers and demands Yuuta to return the flash drive. Although having seen Yuuta return the flash drive, she still felt uncertain about the situation. This leads to her sneaking into Yuuta's room during the night, only to find out that the flash drive had not been returned! Scanning through its contents, she hurriedly rushes to bed when Yuuta enters her room. To her terror, she finds the flash drive crushed due to her negligence in keeping it in a safe place. Yuuta quickly finds out and demands an apology. However, Rikka too, demands an apology from him, resulting in both of them refusing to be the one to apologize first. Will the two lovebirds be able to resolve their argument? [Written by MAL Rewrite]

For the invincible and basically happy punk lads Hiroshi and Toru, what they care about every day is to get a lot of attention from girls and to win the fights against the lads from other schools. Whenever provoked, they just go out fighting and settle the situation no matter what it costs.

The ExWire of True Cross Academy are beset with shock and fear in the aftermath of discovering that one of their own classmates, Rin Okumura, is the son of Satan. But for the moment, they have more pressing concerns than that of Rin's parentage: the left eye of the Impure King, a powerful demon, has been stolen from the academy's Deep Keep. After an attempt is made to steal the right eye in Kyoto as well, Rin and the other ExWires are sent to investigate the mystery behind the Impure King and the ultimate goal of the thief. While this mission has them cooperating for the time being, Rin has never felt more distant from his fellow exorcists. In his attempt to reconcile with them, he undergoes specialized training to control his dark power. However, when the right eye is stolen not long after their arrival, the unthinkable threat of a traitor amongst them leaves them in need of all the power they can get. [Written by MAL Rewrite]