I would look like Shinji. On the smaller side, but not a twig, and very cute in that "awww" sort of way, for a guy. But my personality would basically be my own as it is, except much more outgoing and productive, and not as idiotic.
I would wake up, go to school, find her. "Accidentally" bump into her lightly (like, bumping shoulders or something) one day, quickly apologize and blush. The next day or something I would actually talk to her, maybe ask to sit with her at lunch if I was feeling particularly ballsy. Just talk and stuff for a while. At the end of it, I'd just continue on with the rest of the day. After a few days of this, I'd ask her if she'd want to meet up outside of school one day.
She'd say no.
Months would pass before I talked to her again. I would finally ask her to meet me behind the school right after class ends, and she would show up, probably.
I would confess, and maybe give her a letter.
I don't know what she would do. She would probably blush, stammer a bit, and run away
The next day, she would ask to talk to me in private, where she would tell me that she was a lesbian and in love with Yutaka.
For her, the next day, she would probably feel kind of bad, but go on as normal.
The next day, for me, would end prematurely on the end of a noose. No, it wouldn't, that'd pin the blame directly on her and make her feel bad. I would wait a while and make it look like an accident.