The way they interact, it seems casual, but thinking back i can see it. Toshi cries for Sumi when he realizes Oomiya was Sumi's crush and Sumi thinks "i'll make him fall for me", then they have sex another time and Toshi makes an offhand remark about Sumi being similar to Kyuu and in his mind Sumi says something along the lines of Toshi innocently saying hurtful things, then at the end when Toshi is going home to Kyuu you see that Sumi helped Toshi with something, but Toshi was so distracted that he didn't realize it was Sumi and you just see Sumi meaningfully stare after him as he leaves. He had to deal with knowing Oomiya got married and that meaningful stare was probably him realizing that Toshi was happy now too and giving up on him... ╥﹏╥
The way they interact, it seems casual, but thinking back i can see it. Toshi cries for Sumi when he realizes Oomiya was Sumi's crush and Sumi thinks "i'll make him fall for me", then they have sex another time and Toshi makes an offhand remark about Sumi being similar to Kyuu and in his mind Sumi says something along the lines of Toshi innocently saying hurtful things, then at the end when Toshi is going home to Kyuu you see that Sumi helped Toshi with something, but Toshi was so distracted that he didn't realize it was Sumi and you just see Sumi meaningfully stare after him as he leaves. He had to deal with knowing Oomiya got married and that meaningful stare was probably him realizing that Toshi was happy now too and giving up on him... ╥﹏╥