The Melody of Oblivion Episode 4 - Monster Union Episode Title:Monster Union.Episode Description:Bocca finally learns that the robot creature he fought before was from the organization, Monster Union, who are humans who serve under the monsters, using the robot creatures as their weapons. Keiko Hamasaki, the sister of Kew, and the owner of the inn, remembers her past, and is reminded of why she joined the Monster Union. Later, the robot creature strikes again, and Bocca is faced with it again, giving Bocca a great surprise.