After breaking up with his girlfriend, Natsuno is homeless and spending nights in his office. At a mutual acquaintance's wedding celebration, he meets up with his old school friend Ui, who had confessed to him just before graduation. Natsuno promptly rejected him and they drifted out of contact. Now an accident has left Ui with amnesia, and his first words to Natsuno are: "Who are you?" Hoping to charm the other man into lending him a place to crash for a while, Natsuno lies: "I'm your ex"…!?