The seme is a foreigner came back to japan with his parents and been looking for his first love whom he thinks was a girl. He couldn't remember the names back then since he was still a child and couldn't speak japanese.
The uke who got mistaken very often as a girl when he was a kid --- is what his childhood friend told the seme.

The seme confessed his love to the uke when they were kids. And the uke thought it was him at first and then noticed that he was holding a flower which has the same name as his childhood friend.

that's all i remember ... sorry if my info is so confusing :

Is it the first chapter from this one? ..Mawaru sekai no kimi to boku

Nah not this one. The uke wears yukata all the time

I'm with you, want to reread this manga too!

I believe it's Ai ni Kizuke yo chap.3

yeah!!! that one!!! thanks