"Sperm Donation" is an act where ordinary men provide sperm for couples struggling with fertility. This time, a married couple in their fourth year appears. "I guess it's impossible..." The wife, Ichika, feels anxious about direct sexual activity with the donor, but can't refuse her husband's strong persuasion to try the timing method. Initially reluctant, she gradually becomes overwhelmed by the stranger's penis... Each time it pierces her depths, she reaches multiple climaxes...