Visiting my girlfriend's house, she introduced her sister, Arina Hashimoto, a very beautiful and cheerful sister. Even though she's gorgeous, she's still single. On the first day meeting her future brother-in-law, she always tried to seduce him with her beautiful body, but he firmly refused because he didn't want to betray his girlfriend, truly a faithful man. However, when his girlfriend went out to buy food, sister Arina became increasingly provocative; as a man, he could no longer resist.