A married woman named Yui, age 29, finds herself pregnant and desperately horny while her husband is often away on business trips. Her stepson Daikun, 22 years younger than her husband, has been there to help alleviate some of her sexual frustration. She longs for him to suckle on her breasts and milk, all while riding him in cowgirl position and squirting out her naughty milk! They make love passionately, covering each other in their combined juices, making this stepfamily affair even more intimate.