Mother Kimika has devoted her life to raising her only son, Kazuki, working tirelessly to support his education. One day, she is pressured into marriage by Yamazaki, a man she has secretly admired for years, and after much inner turmoil, she gives in to his advances. By chance, Kazuki witnesses the encounter, throwing his emotions into chaos. Struggling to understand her son's spiraling feelings and determined to guide him, Kimika begins exploring a new path of intimate education.