Chai

Twins(?) or two similar-looking siblings in high school.
Uke thinks the seme is in love with his sister.
Eventually gets to a point where the uke puts on one of his sister's school uniforms to act as a 'replacement' for the seme.
Twist at the end is that the seme has always liked the uke as we see him scrolling through a ton of candid pictures of the uke.

;-;