As a child, Jinta was the de facto leader of the self-proclaimed Super Peace Busters. Jinta was energetic and outgoing during his childhood, but has become withdrawn and isolated due to the deaths of Meiko and his mother.
After Meiko's death in an accident, the group of friends drifted apart, and Jinta eventually became a hikikomori, refusing to go to school and confining himself to his home. As a child, he was in love with Meiko but refused to admit it when asked. This started the chain of events that led to her accidental death. He believes that the Meiko that appears to him is not a ghost, but rather a manifestation of his stress, calling her "the beast of summer". He eventually becomes hesitant to grant her wish out of fear that she will vanish again. Nonetheless, Meiko's appearance encourages him to venture outside and reconnect with the members of the Super Peace Busters.