Why is the dream of young souls in the East a knife?

The plot is so touching. Dream of the Soul of the Oriental Teenager is a calligraphy, and the ups and downs of feelings make people feel like being stabbed with a knife. There are sequels and derivative works such as Dream of the Soul of the East, which are warm but sad. The characters at the scene are Rumiya, Grandma, Bayunzi, Hakurei Reimu, Morichika Rinnosuke and others.