Ohma is a boy? I thought he was a girl.
I'm guessing Ohma was the hiruko in Usami's basement parking. They seem to have the same powers.
Edit: I forgot that about half the kids there are hermaphrodites. So Ohma could be both male and female.
In Chapter 1, Mimihime says to Tokio, "Well, if I think of that, from the outside, two people would come to help me, and among those two, one looks exactly like you."