SSB - Chou Seisyun Kyoudai

This story is about the Shinamoto Siblings, who love themselves more than anything else. This story is also about the mysterious Aisato Siblings. Because these two sets of siblings are similar, it's natural that the boys and girls are friends with one another. Even though they may seem to think "only of themselves," their life motto is that "those of a flock must stick together".