Unaired episode included in the fourth Blu-ray volume. The episode will take place during the same time in episode 16 (episode 5 in second cours) and depict what Eris and Ruijerd were up to outside the main story, as teased by the comment "Goblin Extermination."

Fifth season of Strike the Blood.

The OVA will tell the childhood stories of the main characters, adapting from the first volume of Satoru Yamaguchi's original light novel. Bundled with the seventh limited edition volume of the manga.

A letter is delivered to Lord El-Melloi II informing him of a Clock Tower reunion. One morning, as the reunion's date draws near, Lord El-Melloi II takes a look in the mirror and reels in shock. He is suddenly a full decade younger! Lord El-Melloi II has become Waver Velvet, his former self! Believing himself to be in the grip of a powerful, magically induced delusion, Lord El-Melloi II immediately begins investigating how this could have happened. On the day of the reunion, he makes his way to the gathering of his contemporaries, planning to confront whoever transformed his body and hoping to reveal their intentions. However, when Touko Aozaki arrives, things take a sudden turn... (Source: Crunchyroll)