Anyone know this manga/anime?

I cannot remember the name of this for the life of me. Its a girl who is a bit dimwitted and naive, but she has a crush on a strange boy at school and a gangster-like boy has a crush on her. She has a pretty sister who can read the thoughts of people's hearts. It starts that she finds out the boy she likes is moving away and being saddened by this news, attempts to confess her love to him in a love letter. But because she has no idea what to say she says everything on her mind which turns the letter into a scroll but forgets to mention her name. Does this sound familiar to anyone? Also, if you have any good recommendations for good Shojo manga/anime, please don't hesitate to tell me.