Mario owns a tavern called Mario's Eden that serves breakfast and dinner. Kidou and Illie live upstairs.
They are stern, but lenient and caring. They have feminine mannerisms but uses masculine ones when they need to get a point across. Most people refer to them as a man and some a woman. Mario doesn't seem to care either way.
Somewhat is a parent figure for Kidou, they are unafraid of confronting him and putting him in line.