I really liked this and just got done with it. It's called Hanbun no Tsuki ga Noboru Sora.
It's about a guy with Hepetitis A stuck in a hospital for a few months, and he meets a girl in there with a more serious issue. I'm sure you can imagine somewhat how it goes from there. It made me sad to say the least. Never as in "I'm going to cry", but just a weird sad feeling, like I'll never get hepetitis A and meet a cute girl in hospital like that. Maybe I'll get hepatitis A and end up in a hospital though.
Had a really good OP. These spanish subs and the bad quality kind of ruin it, but oh well.