Suzumi is a gay boy who likes to cross-dress, he does not go by girl, in this short prequel he is just confuse due to his crush on Haruto, he thinks if he became a girl Haruto will fully love him like so, that is why I'm so happy that Haruto accepted him as a boy, I'm glad Suzumi was able figure it by the end of it too
Just added this because it can be confusing, Suzumi is not trans, in the main story he refers himself as "ore" a masculine term for "I" in CH.1
Also
@AleGear96 no it doesn't mean your gay, there are men who like read stuff like this but don't find attraction to the same sex in real life, so enjoy whatever you want