All of them are known to be classmates and students of The Ultimate Academy for Gifted Juveniles. Although, the three don't have a lot of moments together due to Rantaro and Kaede's early deaths in chapter one of the game.
The three had a little moment during chapter one although Miu is not interacting with them in person in this scene. When Kaede and Rantaro discuss some of their more unusual classmates during his Free Time Events, Rantaro mentions that Miu's talent is beyond comprehension for ordinary people like them, but that he understands her thought process and that she likes to be the one on top. Kaede is puzzled by the phrase's wording, and Rantaro laughs awkwardly, explaining that he was only trying to make a joke. This might be the only scene where the trio had the chance to get to know about one another.
Irumamatsu is considered a rare pair in its fandom. It is mainly shipped by people who can't decide between Amamatsu and Irumatsu, and occasionally Amuma. It's rivaled by each character's popular ships such as Saimatsu, Kiiruma and Amasai. There's not a lot of fan art of the three alone, though there is some fan fiction. Irumamatsu currently has 5+ works on AO3.
- Amamatsu refers to the ship between Rantaro and Kaede
- Amuma refers to the ship between Rantaro and Miu
- Irumatsu refers to the ship between Miu and Kaede