All three haven't interacted as a trio, as they are from different games, with Korekiyo also being from a different saga. The only instance of interactions between characters involved came from Celestia and Mikan's event from Ultimate Talent Development Plan. However, all of them share a great number of similarities.
All three are the culprits of Chapter 3 of their respective game, being directly or indirectly responsible for the deaths of two victims; with Celestia killing Hifumi Yamada whom she previously manipulated into killing Kiyotaka Ishimaru, Mikan killing Hiyoko Saionji and Ibuki Mioda, and Korekiyo killing Angie Yonaga and Tenko Chabashira.
All three are known for having the unsympathetic motive for murder, with the motives of all the other chapters in each game usually being at least less villainous. All three are also known for showing off their true colors upon being revealed as the culprits, causing them to shout their equally known catchphrases: Celestia's "Because, because, because!", Mikan's "Forgive me, forgive me, just forgive me already!", and Korekiyo's "Apologize, apologize, apologize!".
With the exception of Celestia, both Mikan and Korekiyo killed two students because of their love for someone else. Both were also forced to kill the second victim, who just happened to be an unwanted witness to their crime.
It's a rarepair to the fandom, but it's shipped because of the similarities between all three of them. Interestingly, as a result of the unsympathetic motives of their cases, the very reason why they're shipped together is also often the reason for why they're hated by some fans. They all have their respective popular ships, such as Celesgiri for Celestia, Band Aid or Hinamiki for Mikan, or Shinnaga for Korekiyo.
With Ruruka being Future Arc's counterpart of a Chapter 3 culprit, killing two people for an unsympathetic motive, she's sometimes included in the polyship with the trio. However, such a version is even more of a rarepair as a result of the anime not being as popular as the main three games.
- Kiyeste refers to the ship just between Celestia and Korekiyo.
- Mikeste refers to the ship just between Celestia and Mikan.
- Tsuguuji refers to the ship just between Korekiyo and Mikan.