Soichi Mawatori has been ostracized his entire youth not only for having a burnt face but also for being a mistress' son. His mother was the sole person who truly loved him, and after her untimely death, he was left all alone. Despite all the odds against him, he refuses to give up hope and strives to become an astronaut. After many years of determination and hard work, his dream finally comes true.

Upon being sent on a mission to the Moon, Soichi discovers a rather strange, feminine, and humanoid creature possessing the ability to communicate with humans. Despite the creature's anonymity, Soichi sees his own reflection in them and names them Io. Following the fateful encounter, Soichi and Io begin to interact and learn more about each other, forming an unusual yet sincere bond along the way.