Cat Ears and Tails
In the world of Loveless, virgins have ears and tails like cats (but also have human ears). When someone with cat ears has sex, they lose their cats ears and tails. So such private parts of one's life is out in the open to be seen and known by everyone. Children often see older people without cat ears as adults, and young people who don't have their cat ears are seen as scandalous. Some even wear fake cat ears around others, like Koya of the Zero unit.

Septimal Moon
Septimal Moon is an organization of 7 members. Seimei was a member of this group and was sentenced to death by a unanimous vote from them, for some sort of crime he committed. For now, we have only been introduce to member number 7, and have heard word of member number 4. Its unknown what number Seimei was.

Wisdom Resurrection
Wisdom Resurrection is a online video game where some associated with the school of fighters and sacrifices mingle and socialize. Seimei played, as well as Nagisa, Ritsu, 7, and now Ritsuka.

Word Spells
Using word spells is how fighter units battle. They use a series of carefully picked words and sentences to attack their opponent and defend their sacrifice.