I KNEW IT!! I wasn't sure that he was her actual father in the last chapter because it cut off some of his face and he appears different with his younger look.
...so.... Eiji's problems have added.... first his double personality, B-1; then the gloomy girl Shinmyouji Rei.... which seems to have hided some things while in collab with Eiji vs. Sai...., and now the true face of Kyouka...