THE NECTAR OF THE DIVINE MANTRA

Sakura, the last surviving princess of a fallen kingdom, is being hunted down for the power of Ambrosia she possesses - the ability to grant divine strength, but only to a human. With no human companion, she decides to summon one from another world in a desperate attempt to find a knight to protect her, but the man who answers her call is less than what she had hoped for. — Description from AniList community (anilist.co).