Hyakkasou 4 Aka Hitomi Yasha Tosuisen no Kyofu

Tang Shuixian, a fearsome woman known as the Red-Eyed Yaksha, confronts a man and his female companion, Botan. Although she initially intends to assassinate the man, she is completely taken aback by the massive size of his member. Instead of killing him, she engages in an intense sexual encounter with him, which Botan eventually joins to form a threesome. A few days after their passionate encounter, Tang Shuixian returns to the man. Defeated by her lust, she offers to sell herself to him as his willing servant.