Is Katarina Nounai Kaigi hentai?
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

ONA · 2020 · 26 episodes · PG-13 - Teens 13 or older
Comedy, Isekai, Villainess
Short specials posted on the official twitter account where the "Katarina Five" will introduce Otome Game no Hametsu Flag shika Nai Akuyaku Reijou ni Tensei shiteshimatta...
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