Abstract
This year-long study investigated how 5-year-old children regulate emotions based on their past to achieve Setsumen (intersubjectivity between people with emotions) in friendship. Results reveal that Setsumen is accomplished when children try to regulate their own emotions and empathize with the other party. Setsumen requires children to attune their own emotions to those of their friends, which occurs when children play together, face difficulties together, and agree with each other. Over time, emotion regulation related to personal history is created between two friends as they continue their association, gradually becoming aware of, and adapting to, each other’s emotions.