When Fuku returns home for the holidays, he finds his stepsister Kasumi—a former honor student who once worked for a major corporation—has become a shut-in after suffering a mental breakdown from overwork. While the family urges her to seek treatment, Fuku feels she simply broke from the pressure of trying too hard to play a part. One day, she suddenly says, "I can't do anything... I'm sorry for being this kind of big sister." Seeing the emptiness in Kasumi's expression, Fuku worries that she might die if left alone. Right then and there, Fuku desperately tries to think of a way to give his stepsister a reason to live. When she says, "There's not much I can do for you, Fuku, but if there is anything, please tell me...", Fuku replies, "I want to see your tits." With her low self-esteem, Kasumi says, "My naked body has no value...", but Fuku denies this and buries his face in her breasts...
