There is no fixed protagonist, and each chapter changes a life.
There is the sweetness of running in both directions, and there is also the cruelty of ending with regret.
Likes and sorrows are random, and the ending is uncertain.
All living beings are protagonists, and all human beings have their own joys and sorrows.
Purpose: All living beings are the protagonists of their own lives, accept all endings, and respect every sincerity.