Whack the Principal!

Kocho o naguro! (校長を殴ろう！) is the 358th chapter of the manga it is also the first chapter of the Repentance Room Arc.

Ms. Hinako becomes overpowered after absorbing a tremendous amount of chi.

Detention
After ditching school to buy some buns, Ranma, together with Hiroshi and Daisuke, were caught by their teacher Hinako. As they make a run for it, she uses Happo Fifty-Yen Satsu to drain their chi. Hiroshi and Daisuke are caught by the Satsu, but Ranma dodges out of the way. Unfortunately he smashes his head into a nearby shop sign.

Hinako ties up the three and presents them to the principal, asking him where the detention room is. The ever joyful principal pulls on a rope, opening a trap door and making them all fall into an empty room. Shouting from above, he tells them that the only way out is to get down on their knees and bow down to a statue and portrait of the principal in the room.

Ranma has had enough and reaches for the metal door nearby, but the doorknob shocks Ranma and remains closed. It's then they notice hand and knee grooves in front of the statue for perfect bowing posture. They also notice that Hinako had fallen with them, who was now pressing Ranma to bow down so they can leave. As Hinako was in her child state, Ranma is able to overpower her and make her nearly bow instead. Hinako gets angry and performs another Happo Fifty-Yen Satsu while Ranma hides behind the statue for cover.

The 50 yen coin was aimed straight for the statue, and after a brief moment she files backward from the immense amount of energy she absorbed before falling unconscious. When she regains consciousness, she use Happo No-Yen Coin Return and blasts the metal door clear out of the way. Ranma notices that she still maintained her adult form after such a large chi blast, and realizes that it must have been from the statue. He theorizes that the statue must have been soaking up the hate and resentment of students over the years and which his teacher fully absorbed.

Chasing the Principal
Hinako heads straight for the Principal's Office, but finds it empty. She fires another Coin Return towards the desk and nearly destroys the entire room. She tells the boys to follow her on her hunt for the principal. As they leave, the principal is seen recovering from behind the door.

Meanwhile, Akane, Ukyo, and Sayuri have also ditched class to enjoy a bowl of noodles. They then realize Hinako and her newly formed gang was right next to them. When they confront them, Hinako remembers her mission and takes off, leaving the bill to Ranma. They notice right away that Hinako was beginning to act like a delinquent, insulting others and leaving graffiti on others' property. Suddenly they notice a horde of schoolboys with nets baskets trying to capture Hinako. After blasting them all away, Akane finds a paper they had all been carrying. It was a message from the principal, telling them that anyone who catches her can have a date with her.

She scoffs at the idea that it could work, but falls unconscious after eating a drugged banana. They start to clamor to get the prize but Ranma takes her away before anyone else. On a rooftop, he wakes her up and reminds her once more of her mission.

They finally return to school and confront the principal. Before she can begin, he tells her that she must first get through his bodyguards, whom he dubbed the Evil Three. They then see three shadowy figures wrapped in cloak behind him.

Cast in Order of Appearance

 * Hinako Ninomiya
 * Hiroshi and Daisuke
 * Ranma Saotome (male)
 * Principal Kuno
 * Akane Tendo
 * Ukyo Kuonji
 * Sayuri
 * Evil Three