Well, if we assume that shoujou has the same abilities as her ancestral, he can copy the looks, the techniques and the strength of a person. Maybe Mitsuomi is avoiding a direct conflict, at least at the beginning. Maybe at the finals he will show up.... and, well, what's best than one Mitsuomi? Two Mitsuomis
Now, one thing i'd like someone to confirm: Souhaku is now within Souchirou, right? Like Souhaku got the shoujou's ancestral body in the past by putting his eye into his body.