An unaffiliated sister who was adopted by a rich man. This man was an unequaled lewd man wearing a good mask. The adoptive man bullied her sister every time. In contrast, her younger sister was loved with a lascivious heart. Her sister who decided to serve as a maid to protect her sister. Taking advantage of her feelings for her sister, her adoptive father leans on her younger sister Yui! Yui who continued to be violated to the extent that her delicate body was destroyed gradually lost her reason.