School Days, the animated series, is based on a H-game (adult computer game) where the player can work towards different relationships with the different female characters and attain multiple endings to the same story.
The visual novel on which the series is based has 12 possible endings the player can get, with one in particular being the "worst ending" that can happen if the player is consistently unfaithful to several romantic partners, to the point that it results in murderous violence among several of the characters. The exceptionally dark second half of the series follows the events that lead up to this ending.
Makoto Ito is credited as a producer in the credits. There is an actual anime producer, Makoto Itô, who has no involvement with the anime at all; he joked about the confusion in an interview.
The opening theme song, "Innocent Blue" was performed by DeviceHigh and released in Japan as a single along with the song, "Dancin' JOKER" and the instrumental versions of both.
All the main characters and some secondary ones share their surnames with those of previous Japanese Prime Ministers and Imperial Court Members.