Gokujou Twins, Waraenai Riyuu Recommendations
Waraenai Riyuu is about a girl who stopped smiling because when she was younger, a guy told her that her smile was ugly, even though he really liked her. Then he moved away. He moves back to the same town years later, and there's some complications.
Gokujou Twins is about a girl who became expressionless because when she was younger, a guy told her that her laugh was ugly.... you get the idea.