This makes no sense since guardianship of a minor in Hawaii ends when the minor becomes 18. The only other guardianship is if one is incapacitated. You do not say where the school is - but in most, if not all states, guardianship of a minor ends at 18. Unless you have some type of disability that renders you as an incapacitated person, the court would reject a petition for guardianship. Check with the school again - see what the school means by "legal guardian." It appears that you don't need one and can't get one. Good luck.