Throughout New Danganronpa V3, Miu appears to have some sort of attraction to Kaede, as she rubs her breasts when Kaede fires back at a spineless insults of hers, saying her breasts are actually pretty big. There are also several circumstances where Miu claims she was turned on by Kaede. When talking to Shuichi in the second chapter, for instance, she says that when the two bowed to her, she was turned on. When Angie Yonaga made a wax statue of the pianist, Miu wanted to see if it had any underwear.
Kaede also seem to care for Miu, and the feelings seem mutual. When Kaede died, Miu was seen to be distraught, compared to her other reactions to the dead. She usually seems unaffected for the most part, even poking fun at her deceased classmates. When Miu grows timid, Kaede grows sympathetic towards the inventor. When she grows to believe the strawberry blonde has no friends in their Free Time Events, she becomes rather worried. Also, Kaede wishes to help Miu become better at communicating, and seems to give passive aggressive advice to the inventor from time to time (mostly in their FTEs.) Unfortunately, it's not always taken as such, and Miu becomes "timid" again due to the yelling.
There also is an instance where Kaede jumps for joy when Miu accepts to make the invention she requested, even proceeding to hold her hands. This causes Miu to sweat, to the point where Kaede asks if her hands are always this sweaty. This could show just how comfortable the pianist is with Miu.
The ship sailed as back as to Chapter 1, as a result of their interaction. That's mostly because their interactions, like any interactions with Miu Iruma, included some sexual themes, such as her insulting Kaede's bust size. Kaede, along with Shuichi Saihara, begging Miu to help her on her knees also helped. What further fueled the ship was the fact that Kaede was one of a few classmates willing to befriend Miu.
When Kaede was revealed to have a twin sister in Chapter 6, some fans have theorized that the twin sister could be Miu Iruma. The reason for that was that both were busty blonde girls with ahoges and wearing pink clothes. The fabricated backstories never revealed whether that was the case, although such possibility seems unlikely.
The ship is one of the most written Danganronpa ships on Archive of Our Own. It also currently ties with Kiiruma for Miu Iruma's most written ship.