Loveless

is a manga series by Yun Kōga. It is serialized in the Japanese magazine Monthly Comic Zero Sum by Ichijinsha and collected in twelve tankōbon as of December 2013. Kōga plans to end the manga at fifteen volumes.

A 12-episode anime television series adaptation was made by J.C. Staff, broadcast in a post-midnight slot on TV Asahi and ABC from April 2005 to June 2005. The anime series was licensed and released in the US by Media Blasters in a set of 3 DVDs in early 2006.

Plot
In his first day at his new school, a then twelve-year-old Ritsuka Aoyagi meets a mysterious twenty-year-old male named Soubi Agatsuma. Soubi claims to be a good friend of Ritsuka's brother, Seimei, who was murdered 2 years earlier. Upon the inspection of Seimei's abandoned computer files, Ritsuka discovers that an organization called 'Septimal Moon' (Nana no tsuki 七の月) was responsible for Seimei's death.

As Ritsuka quickly discovers, Seimei and Soubi acted as a pair involved in spell battles invoked by carefully selected words. Now Soubi is Ritsuka's 'sentouki', or Fighter Unit, and Ritsuka is his 'Sacrifice'. Together, they challenge Septimal Moon to find out the truth behind Seimei's murder and the reason for Ritsuka's amnesia, and form an intimate bond as they unravel the mystery.