A mysterious virus known as \'Algernon\' has been causing deadly incidents around the world. A company called Akamatsu Industries is on the front lines of the battle against Algernon using mecha dubbed Neuronoids. High school students Keita Aono and Hinoki Sai get pulled into the battle against this mysterious force. In their first battle, they encounter a strange mutant with the ability to change into several monstrous battle forms they dub \'Betterman.\'