Reminds me of Arai Cherry's Musunade, Tsunaide, which just finished scanlation on Mangadex. Though that one was a comedy, and this seems to be a lot more drama focused.
yeah that were my thoughts too, I'll be happy to read this one regardless though, since "Musunade, Tsunaide" was also a lot more subtext and this one seems to be going far more directly yuri focused as well as being more drama focused.
So yeah a yuri drama, with basically the same premise as "Musunade, Tsunaide" sign me up.
Also it's unclear to me right now but we'll definitely get to see more later, Erika was in love with Koto, Koto was in love with Aya, but it's not clear if Aya actually reciprocated that love with Koto or not and the mangadex summary does say that all three of them are carrying secret loves with them, so I'd wager either Aya did reciprocate in her own playful way, or she was in love with Erika.
On top of that though given seven years have passed for Koto and Erika I can't imagine Erika didn't at least confess, especially given how they're going to the same college and thus have stuck together since.
All in all yeah how to break a triangle is appropriate here given how Koto and Erika's feelings must have shifted over these seven years and Aya's would not have.