The Melody of Oblivion Episode Rating Graph

While following Kurofune, Bocca and Sayako encounter a dead end, but finds 'Nezumikoukoku', or 'Pyramid Scheme Valley', and also find a dam with a mural of a tear on it. The duo goes to it, and find a beautiful boy with sky blue hair. They also meet up with the artist of the mural, Eichi Hikoyama, who seems to be hired by a woman named Miri Kanaya who owns the dam. Miri also owns mice that gather tears around the world for her dam. Bocca and Sayako pass as art students for Eichi, and stay in the village. The two find out from Eichi that the boy from the dam was neither Monster nor human, and people call him a demon, and despise him. The next day, Sayako found a girl with a large jewel around her neck, and decided to try and steal it. Meanwhile, another robot creature appears in the valley, of which Bocca quickly drives away. While he tries to chase it, he encounters a whole bunch of mice, who attack him. With an odd sound, he realized he was saved by the girl Sayako met. When she saw he was a Melos Warrior, she quickly drew her bow, and pointed an arrow at him. Exactly what's up with this place?

Bocca and Sayoko arrives at a huge industrial region. Sayoko befriends a strange girl by the name of Coco. Coco tells Sayoko that she is involved in a theatrical play nearby. Bocca and Sayoko later meet up with a guy who offers Bocca a job as a security guard. And while Bocca faces a team of saboteurs of the delivery truck that he is protecting, Sayoko is taken prisoner by the guy, who reveals himself to be a member of the Monster Union. Bocca's bow is damaged during battle, but his Aibar machine provides him a more stronger bow. As the battle goes on, the saboteurs which includes Coco, realizes who Bocca is and stops the battle. They show Bocca the contents in the truck and brings him to see someone he knows.

Bocca meets with Kei in the illusionary bus. They share thoughts about their dreams, and Bocca reveals his feelings for Sayoko. He learns that Kei and all the rest of the children that Horu, the monster, has devoured are digested repeatedly. Bocca later finds himself back at the stadium facing Horu in battle. Having faced that very same battle before, Bocca easily defeats Horu. Horu escapes to heal himself. Bocca and Kurofune meets once again, Bocca wants Kurofune to leave the maze, he tells him that Sayoko is waiting for him. But Kurofune wants Bocca to leave instead and let him finish Horu himself. They both exchange 'arrow fire', and Bocca loses. Kurofune seeks out Horu, and finds him healed. Kurofune tells Horu that he has already killed him and that he will never be able to leave the maze. Kurofune fires a bolt of arrow into the walls of the maze, and runs through the walls. Bocca who was trapped in the maze finally escapes the maze and is pulled out of the sea waters onto a boat, into the waiting arms of Sayoko. They learn that the island had sank a long time ago.

Bocca and Sayoko arrives at a tourist spot. Sayoko's investigation into the place reveals that several tourists have gone missing there. They spot the body of Tone's Aibar machine, Skyblue, the blue eyed boy, lying close to the waters. Bocca revives him with the aid of his Aibar machine. They learn that Tone has been taken prisoner at a castle managed by a member of the Monster Union known as Lucky Thoroughbred. Skyblue suddenly warns them that they had been spotted and that the enemy was headed their way. Flying Bunny, a girl in a bunny costume riding a flying board, arrives. Bocca, Sayoko and Skyblue are spotted by her. She goes on an aerial attack. In the battle against Flying Bunny, Bocca's Aibar machine attempts to fly but is unsuccessful. Bocca successfully wounds Flying Bunny, and she retreats to the castle to heal herself. She meets with Lucky Thoroughbred and they exchange some harsh words. Lucky Thoroughbred reveals his intent to set bombs all over the world and then visits his captive, Tone. Skyblue meanwhile, meets up with another Airbar machine, the one who uses boomerangs as weapons. They fight each other. Sayoko meanwhile tries to kiss Bocca, but Bocca hesitates. Sayoko learns why, she realizes that Melody is watching them. Sayoko runs off feeling hurt. She is suddenly greeted by Lucky Thoroughbred in his monster machine. Sayoko however, looks more surprised than afraid. And instead calls him, "brother".

With Sayako and Toune trapped in the castle of Lucky Thoroughbred, Bocca and Koko sneak in to save both. While on the way in, the two get more than a bit comfortable with each other, and Coco tells her story to the boy. Within the castle, a helpless Sayako is reminded of her old family, and of her brother's "achievement" to become a Monster Union agent. Meanwhile, the two Melos Warriors go separate ways. Bocca eventually meets up with Lucky Thoroughbred, agreeing to a race with his robot monster over a lake of water, since if Bocca wins, his friends would be released. At the same time, Koko in off saving Toune, when met up with Flying Bunny, where trouble starts to occur. What happen there? And can Bocca win the race with his flightless Aibar-Machine?