Sato, the business consultant hired by her husband, takes advantage of his absence to demand that Reiko perform masturbation in front of him, promising favorable loan arrangements in return. Thus begins their secret affair. Though initially conflicted—how could she become so sensitive and aroused exposing herself to another man, even for her husband's sake?—Reiko gradually falls under Sato's spell. His thick cock overwhelms her senses, and she finds herself trained to crave it, actively seeking his pleasure. The ecstasy she experiences awakens entirely new sensations within her. This illicit relationship slowly consumes her heart, drawing her deeper into forbidden desire.