My younger sister Yura, who was born from my parents' remarriage, has been teasing me by flashing her panties and enjoying my reaction lately. One day, while my parents were away on their honeymoon, Yura's cute and cunning temptations escalated for four days! "You wanted to see Yura's boobs, didn't you?" In a space where we were alone... my unrelated sister is too Ke'ai... I couldn't keep my sanity anymore and we had forbidden sex! With the limited time we had, we immersed ourselves in sex until the last minute before our parents returned home.