They were brothers who grew up, even if they were not biological brothers, but they were still childhood friends. After that, they went to kindergarten together, elementary school together, and junior high school together. Until high school, they were still in the same class, and then there were two more girls in the class. Later, the two gradually found that they were attracted to their brothers, and the two girls also found that they had a slight crush on each other. Before that, they were originally a male and female couple, and then they slowly became a boy and a girl...
Intention: Things are getting more and more complicated