It was a chapter in a manga, I think. A high schooler recalls his childhood. He had very distinct buckteeth and was teased and called Ratboy. He wore a paper bag over his head. The boy he was in love with just disappears before middle school, but in high school, they run into each other.

I just read this, too, lol. My bad memory...

Nevermind. Just found it! Yume Miru Seiza