Hidamari ga Kikoeru
Mishearing guy uses a dumby boy to take notes for him. He makes lunch for him in exchange. They become friends, but there is more to it...
Yamada To Shounen
The age gap is normally something I dislike, but things were never forced. I think both characters knew exactly what they wanted before doing anything serious. They're cute. It's kind of shoujo-style
Hollow Lovers
A workaholic designer and a lost and poor young man cross path at a bar. They will change each other's lives by showing the other what they lack.
Oh My Hero!
If you need a very cute shounen ai in your life, this might the one you need.
Yuki No Shita No Qualia