Yahari Ore no Seishun Love Comedy wa Machigatteiru.

Synopsis

Yui invites Hachiman and Komachi to the annual summer fireworks festival as thanks for taking care of her dog but Komachi backs out of the offer to give Hachiman and Yui a chance to go together. On the day of the festival, Hachiman and Yui try to compensate for the awkwardness of going out together for the first time by shopping around for some items for Komachi. The fireworks soon begin and the pair run into Haruno while looking for a place to watch the spectacle. Haruno uses the opportunity to explain a little of the complicated relationship between herself and Yukino and laments that Yukino has difficulty in forming meaningful relationships with people. At the end of the festival, Haruno mistakenly refers to Yukino's involvement in the accident but Hachiman brushes it off as water under the bridge. Afterwards, Hachiman takes Yui home and she explains that she would rather Hachiman, Yukino and herself not keep their feelings bottled away and further laments that she would have befriended Hachiman even without the accident, which he rejects based on his own causal reasoning. However as school resumes the following week, Hachiman begins hating himself for believing that Yukino was incapable of lying since she had opted to conceal her involvement in the accident from him. (Source: Wikipedia)