In Tokyo in 1979, four sisters with different personalities accidentally discovered an extramarital affair that had been hidden behind their father's old age.This secret is like a quietly detonated bomb, tearing away the illusion of their seemingly harmonious family and slowly releasing their long-suppressed emotions.The curtain of happiness peeled off bit by bit, and the sisters' emotional world shook accordingly. In shock, pain and confusion, they had to face each other again, and the most real emotional entanglements deep in their hearts again.