Fck i finally found it after going through the "convenience store" tag!! I was finding this desperately cause the uke's so friggin pretty!! I thought seme's an author that's why i mostly searched for it with "author x student" and along the lines in the tags. But boy oh boy did i forget that the seme's actually a band member and a song writer TTvTT
Anyways, I'm happy now that I've already found it and await for the updates for pretty uke <3