Officer from the Blue N°6 that seeks revenge against doctor Zorndyke.
She´s in charge to make Tetsu Hayami, an ex member from the Blue N6, change his mind and get back to the submarine. At first Tetsu refuses to do so, but, after the city were he´s living is attacked by a group of amphibian mecha known as Spiders, he agrees and saves Mayumi. Both of them get inside the submarine and she leaves Tetsu alone with captain Iga. After Tetsu agrees to cooperate the submarine is attacked by a Musca along with some Spiders. Mayumi and Tetsu get inside a grampus, a smaller battle ship, in order to handle with the Spiders wile Blue N6 takes the Musca down. They manage to acomplish their mission but when one of the Spiders is disabled, but not completely destroyed, and Tetsu saves the pilot inside that enemy ship, Mutio, she angers with him, but they get back to the submarine anyway. The Blue N6 travels to his underwater main base and in a conference with the Blue commander Muranami they are told that the plan to end the war against the hybrids for ones at all is to destroy their South Pole main base. Wile this happens the Blue main base is attacked by the Ghost Ship and destroyed in the process, but the Blue N6 and other submarines manage to escape. Tetsu gets lost in the process wile he was trying to pilot a grampus. He´s saved by Mutio and a friendly Musca that takes him back to the submarine. Captiain Iga orders to shoot the Musca believing that he´s an enemy, but Mayumi runs and grabs a grampus saving Tetsu who was inside the Musca. Then, when Tetsu frees his old friend Katsuma, who had been kept inside the submarine as he´s DNA had been modified into a hybrid by the enemy, she escapes along with them inside a grampus, in order to end the war without the use of brute force by getting before the submarines to the South Pole and finding Zorndyke. The travel trough the sea and get to the South Pole. Ones in there they are taken to Zorndyke´s house and the three of them start to talk. Zorndyke explains that his heart is the device that operate the machine that has been changing the earth´s magnetic field´s, and that he is about to die, so there´s no need to destroy the South Pole. Mayumi isn´t able to hold herself anymore and tries to shoot Zorndyke but Tetsu stops her. She calls the submarines and they end the South Pole operation wile Zorndyke finally dies. Along with Tetsu they wait on the sea shore to meet their friends as the hybrids, lead by their commander Verg, leave the land and travel to the deeps of the ocean.