As Ritsuka continues to mourn the loss of his brother Seimei, he endures abuse at home, bullying at school, and the threat of new assassins on his tracks. Can he sort through it all and unlock the secret behind Seimei's death?

After a grueling battle against the powerful Zeros, Soubi is badly injured, and in spite of his training, the pain almost too much to bear. He goes to see Ritsuka, but Soubi's erratic behavior and unpredictable emotions take over, and he abruptly storms away before Ritsuka can care for him. Ritsuka is left tormented and confused...but the mystery behind the death of his older brother is about to take an unbelievable turn. Ritsuka finally decodes the message left by Sleepless and goes to meet one of the members of Septimal Moon!

Ritsuka Aoyagi is a sixth grader, transferring to a new school. Years ago his brother Seimei was murdered. Upon transferring in, he is branded as peculiar - he shows up without his parents, and is aloof toward the other students. Yuiko, an outcast in her own right, befriends him, much to his dismay. Soubi, a Fighter Unit, arrives to meet Aoyagi. Soubi knew Seimei, and Aoyagi lets his guard down momentarily. Midori and his Fighter Unit Ai come with orders to abduct Aoyagi, but are powerless against Soubi. Aoyagi, who seems to be suffering from memory loss as well as personality disorder, wants to reclaim his identity as "Ritsuka." Aoyagi discovers a mysterious last message left from Seimei in which he reveals the identity of his murderer(s) as The Seventh Moon, and that his true name is Loveless. Midori and Ai again try to abduct Aoyagi, but are thwarted once again by Soubi. Aoyagi is confused by Soubi's psychological tactics, who seduces him yet withholds the emotional connectivity which he craves. On the other hand, he slowly warms up to Yuiko, becoming a friend to her. Meanwhile, other rivals appear: Yayoi is jealous of Aoyagi's friendship with Yuiko; and Kio, a university colleague of Soubi, is distraught that a young boy such as Aoyagi could capture Soubi's attention. As a sign of their bond, Soubi asks that Aoyagi pierce his ears. On Parents' Day at school, neither Aoyagi nor Yuiko's parents are present, but Soubi shows up to greet Aoyagi at the entrance. Aoyagi is further entranced by Soubi.

清明は生きていた…!――その思いを胸に、清明と対峙する立夏。 今、二人の絆が試される。