SaiKano
From MinnaHistoryWiki
The saddest love story ever.
Seriously. Boy and girl fall in love. Girl is recruited to house this ultimate fighting machine in her body. Hides it from boy. Boy finds out. They get all sobby together. Decide to run away. Get caught running away. Girl gets taken away. Girl has machine take over more of her body as she continues to use said machine.
Its not emo, its just SAD.