Minotauros no Omoibito

Mighty Minotaurus, ruler and protector of the forest, is a powerful but gentle being. One day, a patrol of humans enters the forest, and he opts to chase them all away, which they promptly do save for Captain Ruviné, a beautiful and tomboyish young woman warrior with a renowned reputation. While she's seeking quarrel, and knowing that they're not a match for Ruviné, in order to find something to fend her off, one of the forest sprites gives Minotaurus a book of human phrases illegible to the forest beings that one of the Captain's subordinates dropped which ends up working, but not in the way anyone expected.

(Source: Mangadex)