Satoru Ikeda

was Sota's friend and the younger brother of Mayu Ikeda.

History
On the day of his sister's school's open house six months ago, Satoru was sick. His mother stayed home to take care of him, and when his sister came home, she felt their mother paid more attention to him rather than to her. When she went out to the grocery store later that same day, his sister came back in the house and placed her scarf over the stove despite his warnings, and then she hid in the closet. He was helpless to do anything once the scarf had fallen and started the fire. Satoru was in a coma for six months after the house fire that resulted in the death of his elder sister.

Mayu Arc
Satoru became a vitcim of Mayu's vengenful, malevolent sprit while in this coma. He woke up when his sister's spirit had been taken by the Soul Piper. After waking up, her informed his mother that Mayu was in the closet, hiding from her. He was allowed to go home a week after waking up.

Quotes

 * "Mom said you're not supposed to hang stuff over the stove when it's on, remember?"
 * "Mayu. She's hiding from you in the closet. Hurry and get her, Mommy."