Kyonyû na shimai: Tanima ni suitsuke

巨乳な姉妹 谷間に吸いつけ

Also known as 巨乳な姉妹　〜谷間に吸いつけ〜, ハミ乳姉妹　ゆれて男あさり, Haminyû shimai: Yurete otoko asari, Majo ni naru tame no mittsu no rule, Big Tit Sisters: Blow Through the Valley

Shion and Miyu, sisters living in the witch world, come to the human world for the witch university graduation exam. The task is to cast a spell on a human man and have him propose to her in the end. The deadline is one month.