In the My-HiME manga series, Mai is still a hardworking person who fusses over Takumi and is reluctant to tell others of her troubles. She is a current student at Fuuka Academy and part of the Anti-Orphan Squad. She and Natsuki are fierce rivals, each one despising the other's attitude.
Mai first appears in chapter 1, crying and passing by Yuuichi. She later is seen in a battle with Natsuki, during which Mai learns that Yuuichi is her (and Natsuki's) Key. Mai, Tate and Natsuki quickly form a love triangle.
Although Mai initially pushes Yuuichi away, they become closer while fighting off Orphans and the Ori-HiME Team in the following chapters. In chapter 22, Mai and Yuuichi kiss while she is recovering in the infirmary, a fact which other characters seemingly know about and later causes emotional stress for Natsuki.
When Mai learns of the link between Childs and Keys in chapter 26, she pushes Yuuichi away so as not to risk getting him killed. She almost becomes a PRINCESS, but instead joins with the Anti-Orphan Squad in chapter 28 to prevent Searrs from opening the Gate to the HiME Star. She and Yuuichi defeat Mikoto and Shiho and make it to the Gate just before Saeko Kuga opens it in chapter 35.
While the Anti-Orphan Squad decides what to do in chapter 36, Mai finds out that Takumi has died from his illness. In the next chapter, Mai once again pushes Yuuichi away from her and falls into depression. She stays at the hospital and is witness to her brother's awakening as the Obsidian Lord. Mai joins her brother's side and becomes the last of the QUEENs.
QUEEN Mai is confronted by Yuuichi and Natsuki in chapter 39, and after a battle is convinced to stop her brother. They confront Takumi, but he is absorbed by the HiME Star and used to create the Star's Child in chapter 43. Mai, Yuuichi, and Natsuki defeat the Child and saved Takumi by using the Sword of Kagutsuchi.