Is Oneechan ga Kita: Hajimete no… Kitaa! hentai?
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

Special · 2014 · 1 episodes · PG-13 - Teens 13 or older
Comedy
This episode shows Ichika's and Tomoya's first encounter. Episode 13 included with the Blu-ray release.
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