Nami Horikawa, an intelligent and dedicated single mother known for her massive breasts, pours her heart into raising her son. However, her biggest struggle comes from an unexpected source—her son's growing obsession with her breasts. Now at an age where every other word out of his mouth is "breasts," she finds herself increasingly uncomfortable as he constantly gropes her ample chest, though she still hopes it's just a phase in his development. Her life takes a shocking turn during a family trip when her secret affair with the inn's manager is exposed—caught in the act by her own son.