During the opening theme "rose", by Anna Tsuchiya, an image of a poster of Sid and Nancy film with the text "love kills" can be seen. The film is also mentioned in dialogue by Nana Komatsu.
Nana Ôsaki gave the nickname of "Hachi" (which means 'eight') to Nana Komatsu, not because their names mean 'seven', but in reference of the faithful japanese dog Hachikô. She said Komatsu Nana resembles a cute but demanding dog.