Mizuho's little sister, who disapproves of Kei but eventually comes to accept him. Initially, she is incensed that a member of the powerful Galactic Federation's elite Observers (which it is revealed that Mizuho has the honor of being its' youngest member) would stoop to marry such an evident primitive. (Conveniently overlooking the fact that she is ostensibly the product of just such a union, claiming that the only time that she had ever seen Mizuho cry was when their father died; the implication of wildly different growth rates between alien and human are suggested here, as Maho is much younger appearing than Mizuho and Mizuho had stated that she could barely recall her father's appearance.) Maho even attempts to use Miruru to hurt Kei. During the process, she learns just how deeply Kei loves Mizuho and vice versa, and she relents, and later actually shows him a degree of affection with a stolen kiss, but she still possesses a playfully devious nature and is not above blackmailing Kei to get what she wants.