While most kids didn't want to go to that 'manly man' camp, often being sent there by parents that either expected that it would help their children against bullies, or by prejudiced parents that feared their boy would become gay if they didn't learn how to be men, (Seriously, parents?) most felt that becoming magical girls instead was even worse.
But not for Maxim. In fact, for ‘him’ that Magical Girl Camp was a dream come true. (Well, the girl part, not the ‘risk your life to save everyone, INCLUDING his parents’.)
Why, do you ask? Because Maxim might be born in a Boy body, SHE know, from the bottom of HER heart, that it was so because of a celestial misshape, that she should be born as a GIRL! Of course, when she said so to her parents, her mom cried while dad whipped her with his belt, then learned of that cursed 'manly man' camp.
So, while most boys choose to either become familiars or guardian beasts, hoping they would stay male in the process, (which forced the organizers to pick boys at random to force them into becoming magical girls) Maxim choose to became one on her own will. When they asked her “What's your name?”, she naturally answered “Maxine.”