Seiren

Seiren (星煉 Seiren) is a student of the Night Class, and is Kaname's unofficial bodyguard. She appears emotionless, never showing anything more than a neutral expression on her face. Seiren is usually the first to defend Kaname from anyone regarded as a threat to his safety. She even threatens to kill Zero when he threatens Kaname with the Bloody Rose. Seiren also appears to serve Kaname in the capacity of a spy or informant, for an example, she is the one who tells Kaname that his uncle, Rido, has risen. In addition, she practices martial arts to use herself as a weapon against enemies. In the anime, Aido says it's out-of-character for Seiren to lie.