The Ayase Eli event song, Storm in Lover, gives me all kinds of EliUmi feels.
Like, it’s clearly girls singing and they talk about their lovers’ perfume -- not cologne, but perfume -- and wanting to embarrass/excite the other but not scare them away...or “the rhythm of the waves” -- as in ocean or Umi -- “urges you to embrace me”...just, yes. It’s all very good.
Basically, I just picture this as post-anime, the summer after Eli graduates. They miss seeing the other a lot and so Eli reaches out to Umi and invites her to visit her for a few days. It’s all done under this guise on both their ends of catching up and Umi taking the chance to visit a good university to see if she’d like to go there and it just grows from there.