In the Japanese version, Saio's voice sounds more like a teenager's during a flashback scene where Aster is still a little kid. I'm guessing that puts him in the 20-something range. So I don't know what the heck Duel Academy was doing by letting Sartorius/Saio be a student there.
But.. you're very inviting and nice to your other friends here? Are you too old, that's why you feel uncomfortable to exchange casual conversations? Mustn't that be the other way around, as experience and wisdom will make you less shy and wary of other people. Also, why do you think I'm a troll? Because I have no username as of this moment?
She's had a few c-bullies if you need an answer, she's not that old btw I don't know her in person, but everyone used to call her a.....uh maybe I'm getting deep into this....you should ask her confidentiality