In his later years, Dr. Light, worrying about the future of Earth, developed his magnum opus, the battle robot Mega Man X. As the "X" in its name signified, this battle robot was given "limitless evolutionary potential": the power to grow and evolve as he fights. To assist X in his future battles, Dr. Light developed a great number of armors, and after an incident occurred where an unknown computer virus came from space and caused robots to become violent and riotous, he also hypothesized that X could battle robots infected by viruses. To that end, he equipped X with the perfect virus counter-measure. However, X was not just a battle robot. He was also intended to be a new generation of "thinking robot", having advanced mental capacities roughly the same as a human’s. Dr. Light made X so that utilizing his conscience, he is capable of thinking, feeling, and making his own decisions through the "act of worrying", which he considered a new epoch in robotics. Because of these advanced mental capabilities, X presented many problems inconceivable in existing robots. As this was the first time that this experiment had succeeded, there was a danger that X may worry over or question even the absolute requirement for robots, “Robots may not harm humans.” If the act of worrying extended to matters that by the nature of robots must not be questioned, it would be disastrous. Dr. Light figured that in the worst case, if a robot were to harm humans deliberately, humankind would tremble with fear the like of which was unknown even in the days of the “Dr. Wily” incidents. As such, also taking into account X and his armors' combat capabilities, Dr. Light concluded that X was an extremely dangerous being that could become a threat to mankind. To determine X's reliability, Dr. Light considered subjecting X's cognitive program to 30 years of ethical testing, but because human life is short and fleeting, Dr. Light would never live to confirm the safety of the X project. It is for that very reason that he decided to seal X away in a capsule, hoping that he would be discovered in a far flung future, urging through a warning that the capsule should not be opened before the aforementioned 30 years had passed.

Though that was his logical conclusion, his feelings had always considered his final creation as a hero that would fight for justice and peace for all people; not as a robot potentially dangerous to humankind. Because of this, he talked to X about how he feared that humanity was not yet ready to accept him. According to him, humanity was not yet mature, and they would judge X's name, limitless potential, and human like mental capabilities as something to be feared. Making clear his true intentions before sealing X away, Dr. Light continued telling him that he considered X as the world's one true hope, somebody that could guide the people of the future. These same feelings he also left in a message to whoever would find X, but at the same time also expressing his concern that X would be swept up in a war called "progress." As Dr. Light himself expressed, there was little chance he would live another 30 years to see X come into the world. The construction took a very long time, to the point that Dr. Light had aged considerably by the time of his completion. His health failing, he died soon after sealing X away. He continues to live on, however, as a sentient hologram, who aids X in his battles by upgrading his armor with stronger enhancements.