After marrying into his wife's family, Shion Sato, the wife's younger sister, returns home to give birth. Recently, along with his wife and in-laws, he has been helping care for her during her postpartum recovery, witnessing firsthand her struggles with newborn parenting. One day, while talking with Shion, he notices milk seeping through her clothes, dampening the fabric over her breasts. Embarrassed, she quietly excuses herself to change. Her retreating figure leaves a lingering impression—an intimate, bittersweet moment hidden within the ordinary.