Is Hello! Lady Lynn hentai?
No
Rated G (All Ages) on MyAnimeList and not tagged as Hentai.

TV · 1988 · 36 episodes · G - All Ages
Drama, Shoujo
This is the second series of Lady Lady. Every year at Lynn's school, an honorable “Lady Quest” is given to the most sophisticated lady. Lynn strives to receive this honor. (Source: Toei Animation)
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