Do you know which book this is?

Hi, I need your collective intelligence.
I once read a book, it was a love story. A nerd who lives in Japan meets a girl and falls for her, and he writes in an online forum about it. You can read what he writes and the answers of the people who try to help him to get her. It was really funny and heartwarming but I was 13 when I read it, it’s been been like 12 years. Googling doesn’t work. Do you know which book this is?

by RatKid__