Is Koi to Senkyo to Chocolate: Koi Imouto! hentai?
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

Special · 2013 · 1 episodes · PG-13 - Teens 13 or older
Drama, Harem, Romance, School
Unaired 13th episode released on the 7th DVD/BD.
View on MyAnimeListShare
Check another title