Maze "Oneni-sama, The Eraser, Mei/Akira Ikaruga"

About

The heroine of the story. She accidentally saves the life of Princess Mil when her house falls on Mil's would-be murderer (much as in the The Wonderful Wizard of Oz) upon falling into the fantasy world. After that she becomes extremely protective of Mill, who often shows intimate feelings or sexual advances toward Maze. She is a natural pacifist when the story begins. She has considerable magical ability but initially is much less effective at using them while a female. Maze is a fusion of Mei and her brother Akira who switch places at daybreak and nightfall. During the day Mei is dominant, while at night Akira is. Maze was brought from the real world as the Eraser to correct an imbalance.

At night Maze turns into a male with a distinct personality from the daytime female form. He loves to fight, to the horror of the female form, who can be seen trapped in his head shouting at him wherever he tries to fight. In male form he has vastly increased magical powers. He is very sexually predatory towards almost any pretty girl he meets. Like the female Maze, his memories are mostly wiped or jumbled upon leaving the real world, though they start to recover over time. He is initially portrayed as a sex crazed, violent monster with little personality, but in time his personality emerges.
In the real world he and his sister Mei shared a taboo love that led to him being outcast by their parents. In time both halves of Maze fall in love with each other again, even though they can only meet each other physically during sunrise and sunset. At the conclusion of the TV series, they choose to not go back to the real world, as this is the only world that they can share their love. The Japanese character for "Akira" can also be read as "Mei" and thus the name "Maze" comes from the term "Meis" as in "two Meis".

(Source: Wikipedia)