Sousuke Nekome is the antagonist of the series. He is a former acquaintance of Tamako Harakawa, and a collaborator in Isako's quest to open the door to the "other side". His ultimate aim is to bring down the Megamass company, due to his father's firing from the company; his brother, Takeru, becomes disenchanted with his older brother's effort over the course of the series.