Is Overlord Movie: Ple Ple Pleiades hentai?
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

Movie · 2017 · 2 episodes · PG-13 - Teens 13 or older
Action, Comedy, Fantasy
Initially aired in theaters. Later released as specials bundled with the Blu-ray and DVD volumes of Overlord Movies 1 and 2.
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