Mr. Morimoto is a Japanese video developer, seen in "Chuck Versus Tom Sawyer", who developed and wrote the classic arcade game "Missile Command" which is also at the heart of the episode.
Chuck's flash on his name revealed that Morimoto worked for the Japanese military and was in charge of actual missiles, loaded into a satellite that is laying dormant in orbit. Morimoto put the launch code for these missiles inside every Missile Command video game machine and set the machine to only give the code once the player had go to the Missile Command kill screen.
Team Bartowski break into Morimoto's company where Chuck finds him playing Missile Command while listing to Rush. He reveals that he hid secret codes to a secret deadly satellite on the secret final screen but says that he is the only one capable of dealing with the complex maths to get to the final screen. He also comments that the game is is based on the "music of the universe". Chuck tries to make Morimoto leave but he says that there is a bomb attached to the game that will blow up if he doesn't play. Casey appears and drags Chuck out of danger and the bomb detonates killing Mr. Morimoto.
Chuck is later forced to play Missile Command in an attempt to gain the code and stop the missiles that way instead of the NSA's plan to shoot it down which will result in "Acceptable civilian casualties". He flashes on a bystander's Rush jacket. The Intersect correlates the Rush music to the game. Remembering Morimoto's words about "music of the universe" being the key to win, he sends Morgan to find Rush music and is then able to play to the final screen in front of the crowd.
Chuck plays the video game perfectly and before long arrives at the kill screen, where he is presented with the missile launch code, which he gives to Sarah.