Kagehime

The story follows Souichirou Niimi, a third-year art college student, who is dedicated to creating sculptures of beautiful breasts and seeking the ultimate beauty. One night, he is attacked by a youkai and meets Kagehime, a Shadow Princess who fights youkai. In order for Kagehime to operate in the human world, she needs a physical body, and Souichirou agrees to create one for her.

(Source: Shounen Gahousha, translated)