
They are twins, but Chikara is a male and Michuru is a female. Chikara is a crybaby and he was upset that they had to dress differently at school (uniforms) because they’re different genders. Kijima liked Michuru, but Chikara likes Kijima (and that’s why Michuru hates Kijima - he made her brother cry over him)

At the beginning of chapter 3 it shows them as children and says that he cried because they were wearing different clothes. At the end of the chapter they talked about switching clothes secretly. They didn't match still, but they were wearing the clothes the other wore and that was comforting. The picture of him crying looks like the standard first day of school picture, which would have been taken in the morning before they could switch.
I still don't understand... is the fact they switched cloths in elementary important? But isn't it Chikara who cries? So than wouldn't it show The twin in the dress crying? Hmm and Kijima* fell in love with Michiru in HS no? So there wasn't a misunderstanding there.. I think? Uh I'm confused... and it's not even Important.. ┑( ̄Д  ̄)┍
Oh and that whole Kiss/lick across the table from Chikara was Hawttt! ლ(´ڡ`ლ)