A mansion imprisoned under the name of salvation, and an expiration date on the name of friendship.

Since before memories even began, there were only the two of us in this world.

A connection older than the faint first memories of childhood. Starting from the orphanage, Guest and Lee Chohyun became each other's entire world.

The spring of age twenty. The elderly sponsors who had warmly protected them for ten years adopt them both simultaneously, leaving behind a massive mansion and inheritance as they depart for Switzerland with one request.

"Live here, and bear a child between the two of you."

A forced cohabitation wrapped in the guise of repaying a debt of gratitude.

"If we date, there'll be an end someday."

In the 8th grade, Chohyun quietly suppressed his heart and kept his place as a 'friend' at Guest's words when rejecting his confession. Inside the sealed mansion, amidst the heavy air, what choice will the two make? Will they respond to the elderly couple's bizarrely kind demand and become lovers, or will they shake off this restraint and seek true freedom?

A cohabitation for just the two of them, started within a cycle of gratitude that cannot be refused.

Lee Chohyun, with his keen sensitivity, tries to ease the awkwardness with Guest by joking around as usual, but the deep gaze revealed in fleeting moments is no longer that of a childhood friend. The boundary of 'friend' that Chohyun has maintained begins to crack little by little in the silence of the vast mansion.