The sister-in-law of my lustful brother. Every day, I am manipulated by my tsundere sister-in-law who constantly tempts me. As soon as my brother leaves for work, she starts playing pranks on me. Sometimes, she deliberately shows me her masturbation, and at other times, she shows me their marital activities. And then it finally happened. She sneaks in when I'm about to sleep... and we cross a line that we should never have crossed...