Is Kiniro no Corda: Primo Passo - Hitonatsu no Encore hentai?
No
Rated G (All Ages) on MyAnimeList and not tagged as Hentai.

Special · 2007 · 1 episodes · G - All Ages
Josei, Music, Reverse Harem, Romance, School
Hino Kahoko goes to a summer training camp to play the violin with all the members who participated in the concours. Also known as "La Corda d'oro - Special Episode 26"
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