The brothers and sisters have lived their lives as if they were close to each other since they were young. Despite having special feelings, he held back...but the truth revealed by his parents on his brother's birthday...they were step-sisters.

They are brothers, but for some reason they instinctively attracted each other to each other for a long time. However, this is a faint love that never comes true. Before long, they realize that they are both male and female, but they endure their efforts with rationality. However, on his brother's 20th birthday, his parents reveal that they are actually step-sisters. My little sister happened to hear about this. Late at night when I was asleep that day, my sister came to my room alone... The feelings of each other, which had been suppressing up until now, explode! They are intensely pursuing each other's romantic feelings through intense sex!