The leader of the Corruptors. At first, he is a "good" program, created by Dr. Inukai to manage and maintain the vast-growing ComNet. His contact with Yui made him want to "live," and later, to create a world where he could "live." Dr. Inukai, who saw the change in Grosser, decided to create the Correctors to restore him to his current status. When Dr. Inukai chooses Haruna as Corrector, Grosser, who was fascinated with (arguably "loved") Yui from beginning, manipulated I.R. and set Dr. Inukai in accident, so that Yui would be the Corrector instead of Haruna.

(Source: Wesker_CDA)