Saya lost her husband Yutaro in a car accident soon after the birth of their son. Afterward, Saya dedicates herself to protecting her son, but has no family to assist her and suffers various hardships while living as a single mother. However, after his death, Yutaro is miraculously able to help Saya by possessing the bodies of other people in the strange town Saya moves to called "Sasara".