* STORY:
Just when everyone thought peace had finally settled on the world, a strange series of biological events started to occur. The world was shocked by a series of earthquakes and, concurrently, plants throughout the world began to die. As news reports began to flood televisions across the globe about these catastrophes, the infamous Dr. Wily made an appearance on TV, shocking the world. He announced that he was somehow behind these events and that unless the populace cooperate and give in to his demands the world would soon be doomed.
However, little did everyone know that Dr. Wily was being forced to cooperate with a group of invaders from outer-space who called themselves the Constellation Droids. These powerful Robot Masters, all named after the twelve signs of the Zodiac, except for their leaders, Luna and Apollo, had taken over Wily's lab and forced the evil scientist to cooperate with them under threat of death.
Dr. Light, renowned robotics engineer and pacifist, once again called on Mega Man to go after the powerful Constellation Droids and the evil Dr. Wily. However, Duo, a member of the Intergalactic Police Force who had helped Mega Man during the "evil energy crisis," returned to Earth to assist with the take-down of the Constellation Droids...
Mega Man, Auto, Eddie, the newly-rescued Proto Man, Fan, and several others are forced to bring the Constellation Droids off of their high-horses. Once Luna and Apollo are defeated, however, the droids inform Dr. Light that they had come to Earth seeking technology that had the capability to restore floral life to their planets. However, the first person they met was Dr. Wily, and Wily used some sort of device that managed to take control of them and used them to destroy the plant life on Earth. Wily had hoped that with plant life dying all over the world the governments would give in and pay him to stop the virus from completely engulfing the globe. However, Apollo and Luna help Mega Man and his team put an end to Wily's scheme and, once finished, they return to Light Labs where Dr. Light constructs a device that returns the Earth's atmosphere to its normal state, allowing plants to regrow once again. Then, Light constructs a replica of the device so that the Droids can take it with them to their home planets.