[2] 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 most immediately noticeable aspect of the story is that many characters are kemonomimi—cat-like features (in this case, ears and tails) are universal from birth, so there are as many catboys, including the protagonist, as there are catgirls.

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.

As Ritsuka quickly discovers, Seimei and Soubi acted as a pair involved in spell battles invoked by carefully selected words.

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.

Loveless focuses on "the power of words in creating our reality, the meaning of memory, the strength of family, and the loss of innocence".

The most notable is the series finale, which was written specifically for the anime and left the storyline open to the possibility of a future sequel.

[50] On September 8, 2006, a vocal album featuring songs performed by Konishi Katsuyuki, Junko Minagawa, and Jun Fukuyama was released.

[54] The Book Report's Robin Brenner liked the art, describing it as "breathtaking --- fluid, dark, and full of slicing edges".

Brenner also commented that the series is "the kind of manga that startles a reader with just how close it treads to taboo lines without ever crossing over into true transgression.