Leon is an eleven-year-old who attends the school where Rien volunteers. He is a shy little boy who is often made fun of at school by the other kids. His two best friends are the Rupple siblings, Chris and Claire. In their triad, he is usually the unwilling one who keeps them from getting into trouble.

Recently, Leon's mother tragically died of a common illness. Because of the possible contamination, Leon wasn't able to be with her in her last hours. He shut himself up in his room for several days after her death except on occasions (according to Claire) when he will visit the gravesite without supervision.

Leon's parents worked together as a cobbler and seamstress. Mrs. Greenstone also played piano. She taught Leon the basics, but the rest is up to him to learn now on his own.