Noshinto Gong is an underground boxing ring in Hole.
Nikaido, and may other humans were lured to the place by the promise of money if they beat Red Brake, in reality the place was a clandestine human sell point for Magic Users, were the people defeated by Red Brake were sold to sorcerers by the Magic User who gave Brake his inhuman strength.
Kaiman, worring for his friend disappearance, went to Nikaido's room where he found a flyer of the boxing event, he knew she went so she would have enough money to pay for the restaurant bills (most because Kaiman never pay anything he ates there), enrolling in the same contest, Kaiman fought Red Brake, easily overpowering him at first but Brake inhuman strength almost killed Kaiman. The place was shut down by them once Nikaido killed the sorcerer that kept her captive and stole all his money and the money price to pay the bills (Kaiman said this was illegal but coul not complain anymore because this, in essence was all his fault for never pay his gyozas).