Is Shi Yi Chang An: Mingyue Jishi You hentai?
English title: Memory of Chang'an
No
Rated PG-13 (Teens 13 or older) on MyAnimeList and not tagged as Hentai.

ONA · 2020 · 12 episodes · PG-13 - Teens 13 or older
Historical, Romance
Young and fierce Princess Emela of Xiyue is traveling to the city of Chang'an to marry the reserved and solemn ninth prince of Tang, Li Qiang. While still on her journey, she already becomes the target of a rebel ambush. However, the princess must not only face the rebels but also break the fortress around the prince's heart. Taking the name Li Mingyue after her wedding, she is determined to make her marriage work to keep her country safe from war. Unfortunately, amid a court rife with treachery and conspiracies threatening the peace, the newlyweds will need to cautiously navigate the complex waters of both state and private affairs. [Written by MAL Rewrite]
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