Noin is a good friend of Zechs from his days at the Lake Victoria military academy. After graduation, she joined the academy's staff, and now trains new Specials recruits in the art of space combat. Though Noin is a formidable mobile suit pilot, she doesn't much care for fighting, and she often uses her influence with OZ's leader [Treize Khushrenada] to try to resolve crisis situations peacefully. She is deeply loyal to Zechs, and protective of him and his younger sister, eventually becoming a Special Guard of the Sanc Kingdom in order to protect Relena.

In Frozen Teardrop
At an unknown date, Milliardo and Noin marry and have twins, Naina and Milou. While Zechs leaves with Naina to travel Mars under a new alias, Noin stays behind with Milou. Her elder brother, Nix-Deuf Noinheim, is the President of a large Corporation and takes Milliardo's name as his own alias, under which he becomes the first President of Mars. When he is assassinated by an anti-Mars Federation rebel group, Noin and her children attend the funeral- notably not shedding any tears for the dead "Milliardo", with Zechs standing behind them.