The Jo brothers, Jo Gyu-bin (uke) and Jo Eun-bin (seme), were raised in a family that many envied, but their bond was so strained that they hadn't shared a proper conversation in more than a decade. Then, an unexpected incident causes Eun-bin to suffer from amnesia, reverting to the mental capacity of an elementary school child. Gyu-bin takes it upon himself to care for Eun-bin after the accident. As he struggles to manage his adult brother who now behaves like a young child—having tantrums, stopping mid-walk to sit down, and clinging while crying—Gyu-bin is taken aback when Eun-bin sneaks into his room late one night. "Hyung, my pee-pee hurts." Eun-bin cries softly, not understanding what an erection is or how to relieve the sensation through masturbation. Gyu-bin, caught off guard, looks at him and, partly out of frustration, ends up engaging in sexual relations with him. Gyu-bin recognizes his error but initially brushes it off, thinking, "I'll just keep him entertained until his memory returns. Even once it does, he'll be too ashamed to disclose anything to anyone." However, this way of thinking soon drags him into a situation he cannot escape.