Kaoru Jinguji plays a grieving widow raising her son, Takeshi, alone. As she reflects more on her future, she feels it would be lonely to live only as a wife and decides to seek a new partner. However, with no suitable men appearing, she devises a bold plan: seduce her son's friend now by passionately kissing him with her long tongue, marking him with her saliva, and securing him as her future husband years down the line. While sneaking behind Takeshi's back, she takes her first step toward fulfilling her desire.