Koito Nagase

Koito is Ai Ohto‘s first friend. Because of her friendship with Ai, she was bullied at school. She is very calm by nature and is able to find good sides in all situations, as shown in her reaction to being bullied at school. She is also kind and gentle, especially towards people she cares about.
Koito's eventual suicide is what leads Ai to become a shut-in, avoiding school and refusing to speak to the teacher when he visits her home. It is for Koito's sake that Ai begins using the Wonder Eggs.