Nagato Yuki-chan no Shoushitsu: Owarenai Natsuyasumi

長門有希ちゃんの消失「終われない夏休み」

An OVA bundled with the 9th volume of the Nagato Yuki-chan no Shoushitsu manga.

This spin-off of the Haruhi Suzumiya series takes place in the world of the "Disappearance" arc of the original novels, focusing on the high school life (and romance!) of a tentative and bashful Yuki Nagato.

(Source: AniList.co)