Angie, Kaede, and Rantaro rarely have interacted with each other, likely because of Kaede's and Rantaro's early death's. Although they haven't interacted much neither of them are shown to be on bad terms with each other. The three are them are friends and students in the Ultimate Academy. Unfortunately, all three had died, Kaede and Rantaro died in Chapter 1 while Angie died in Chapter 3.
In Rantaro's case he seemed to find Kaede cool, because of her leader role among the other participants of the Killing School Semester. Later, Kaede was framed to be Rantaro's murderer and got falsely executed for Rantaro's death. It was revealed in Chapter 6 that Tsumugi Shirogane merely framed for both Kaede and Rantaro's death, to get her out of the way. Since she considered both Rantaro and Kaede a burden for the Killing School Semester. In Angie's and Kaede's case. Angie or Kaede have barely interacted with each other. At the same time, Rantaro and Angie rarely and barely interacted with each other. But there are some parallels between Angie and Rantaro's personalities, both are able to stay calm when everyone else may be stressed and can take control of a situation, both in their own ways.
Kaede is shown to be liking Angie and Rantaro. She barely interacts with Angie due to her early death, but is implied to be on good terms with everyone in the killing game including Angie and Rantaro. She is obviously good friends with Rantaro on the other hand. The two are shown very close throughout the game, and Kaede later on feels very sorry for the death of Rantaro, who she thought she killed. After Kaedes death, Angie is seen very sadden by the death of a friend of hers. As for her early death she doesn't interact with the two often.
Rantaro is shown to be liking Kaede and Angie. However he doesn't seem to interact with Angie. But, Rantaro is shown to be on good terms with her. However, him and Kaede are good friends. As for that the two have a lot of interactions, he is shown to respect Kaede heavily. Kaede and Angie were seen sadden by the death of Rantaro. As for his early death he doesn't interact with the two often.
Angie is shown to be liking Rantaro and Kaede. She barely interacts with the two, but is shown to care for them greatly. She made wax effigies for the two later on, along with Kirumi and Ryoma. After their deaths, Angie is shown sadden. As for their early deaths, Angie is shown not interacting with them a lot. But she is shown to respect them as she is friends with them.
Amanagamatsu is a rare-pair among the Danganronpa fandom. The ship sailed due Rantaro's, Angie's and Kaede's different personalities. Rantaro's high and positive opinion on Kaede helped the ship status grow. In Angie's report card it's also mentioned that she likes avocados, as of the majority of the fandom jokes about Rantaro being an avocado due to his hair color. Nonetheless, Amanaga, Amamatsu, and Yonamatsu are all a bit more popular as separate ships and not as poly/full one. There's also not that much fan art depicting the three.
Otherwise, the ship easily gets overshadowed by far more popular ships. For Angie being, Shironaga and Shinnaga. For Kaede being, Irumatsu, Saimatsu, and Nursery Rhymes. And lastly, for Rantaro being, Amaguji, Amasai, Oumami, and Amamiibo.
- Amamatsu refers to the ship just between Kaede and Rantaro
- Amanaga refers to the ship just between Angie and Rantaro
- Yonamatsu refers to the ship just between Angie and Kaede