L (エル El) is the leader of the Student Council and is in control of Exaclan. He currently owns 1 star, although it is not Aoi Tsuki's weapon (as Tsuki is L's possession).
Asagiya Karin (浅黄谷 カリン) is L's disguise as Himoto Sora's ally. He wears an eye-patch over his right eye, where his mask usually is. Apparently, Aoi Tsuki knows that Karin is actually L when Sora introduces Tomoko and Tsuki to him. Tsuki is horrified to hear his name, as looks at him with disgust as she drags Sora off.
When Karin's father was dying, he revealed to Karin that their family was not actually chauvinistic, but they were only keeping up appearances for the sake of the other families who believed in them. His father then gave him a book on the Story of Paradise.
Sora informs Tsuki of this man who saved her. Tsuki gives Sora a plan to save the girls, physically and emotionally. This plan involves the participation of a male ally and so Sora, in upholding Tsuki's plan, searches the school for the "kind boy wearing an eyepatch". After being conned and struck by two boys in the forest, Karin saves her again.
In the Secret Garden, Karin reveals that he belongs in the "Shuuei Class" or Special Class. He does self-study here since he doesn't wish to discomfort others. Sora questions him to determine if he is ally-material then manages to "persuade" Karin into joining her side.
Sora immediately brings Oashi Tomoko to make a vow with him. After Sora leaves, Karin sheds his disguise and reveals himself to be L.