- Cash Cow Franchise: One of Otomate's flagship franchises, along with Hakuouki and Hiiro no Kakera.
- Fan Nickname
- Although the heroine lacks an official name, Lin is the most common name used by the fandom.
- The two sides of Ukyo have their own names. The kind, slightly timid Ukyo is called Omote!Ukyo (Surface Ukyo) and the murderous, insane is Ura!Ukyo (Below/Other Ukyo).
- No Export for You: So far, there has been no news of an official English release for Later, Crowd, or World.
- What Could Have Been: Some characters changed vastly during the creation of their looks. Particularly interesting are Ikki◊ and Kent◊. Looking at the rough sketches, the two of them ended up switching appearances.
- Kent was originally designed to be a pretty boy with gentle eyes, and a clover painted on his left cheekbone before his design was fully set. His penultimate sketch also shows that he might have been originally intended to be a smoker. Ikki ended up having the pretty boy appearance and painted-on spade.
- Ikki's first rough sketch showed him with an intimidating stance, rather spikey hair and a long coat with belts on it. Another sketch looks closer to his set design, but wearing glasses. The idea of Ikki wearing glasses was kept in Later, where he uses them for reading. Kent ended up with the coat and spikey hairdo, as well as wearing glasses.
Trivia / Amnesia: Memories