I think that sounds like a good idea. Letting Reina have authority over majority of the campus is a no brainer, since she is Headmistress. I'm not a huge submissive, but I wouldn't mind having Reina shackled to your character in some way. Maybe it could be like in order to get the Morimoto name in power at the Academy, a few arrangements were made between them. She gets power, but has to return a few sexual favors, which she would be fine with anyway.