Is Ai (ONA) hentai?
No
Rated G (All Ages) on MyAnimeList and not tagged as Hentai.

ONA · 2012 · 1 episodes · G - All Ages
Avant Garde
The circumstances responsible for the person's pained expression remain unknown. However, it can be surmised that love is responsible for the anguish they feel. [Written by MAL Rewrite]
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