OMG OMG LISTEN TO ME. There IS a Shirousa route!!!! In the novel :3 It's not that good though... I hate what they did with the route. I'd tell you what happens if you don't mind spoilers (or if you're not gonna read the novel at all). I also wanted to see them end up together the most but the author did them wrong ╥﹏╥... If I was the one to write it it would be a banger route but here we are
So BASICALLY... The author made Shirousa "accept" her girly side because she was in love with a boy ಥ‿ಥ She stopped working out and turned into a "girl" because she wanted to be the right person to get together with Akira. WHICH IS STUPID?? My girl could have had all her muscles, her not so feminine personality AND date Akira. I was so disappointed that they didn't get anything good writing or even nice scenes really :(
They tried to explain it in a way that "she was not being herself to protect her brother, so she went back to her real self ^^" and I find it to be a nonsense... I think she was working herself too much to protect her brother, real. But "turning herself to be the most feminine classic girl that she's supposed to be" felt REALLY sexist. It was not needed for them to end up together :')

Honestly it won't be bl then but if shirousa san was a route it would have been so interesting. I feel like mc and shirousa would kinda like understand each other and their shared experiences would make for a good story and all the route characters honestly feel like better friends than lovers