Kaname and Kyoko are chased by a group of guys. Kaname recalls how she mistakenly angered the guys by landing a punch on one of them as they were bugging Kyoko. Now they're both on the run, but Kyoko falls down. The guys approach the girls, but then as they're about to strike, one of the guys' arms is held back by another guy in a bandanna. He beats up the bad guys with a couple of kicks and they run off. Kaname is about to thank him, but he refuses the gratitude because they're a bunch of lowly women. Kaname is offended but bandages the guy's wound anyway.
The next day, Sousuke and Kaname discuss a recent school assignment from the Council. They are serving an eviction notice for a dilapidated clubhouse. The clubhouse turns out to be from the Amateur Karate Club. The Karate guys, three of them (Marron, Waffle and Chocolat) don't want to leave and if they want them out they'll have to use force. The Karate guys offer Sousuke a deal. Sousuke chooses an opponent, and if Sousuke defeats him, they surrender the clubhouse. If they lose, Kaname has to join the club as the manager. Sousuke agrees before Kaname gets a chance to protest.
Marron is up first. He charges Sousuke, but Sousuke pulls out his shotgun with the blank shells, and knocks him to the floor. Sousuke then unloads the shotgun shells on Marron's bottom. Sousuke declares, "I win." The other guys protest. In martial arts, the use of guns is taboo. Sousuke respects that, and the next guy is up to challenge him.
Waffle charges Sousuke. Sousuke pulls out a fire extinguisher and sprays him with gas. Sousuke declares victory again, but the karate guys tell him that's not right either, and that he has to use his bare hands. Sousuke complies.
Chocolat, the third guy, is up now. Without any weapons and just his bare hands, Sousuke prepares for the attack. As Chocolat charges, Sousuke throws a grenade in the air, telling him to catch. Chocolat is distracted as Sousuke nails him with a sucker punch.
More protesting ensues. Then a guy at the door makes his presence known. It's the same guy who saved Kaname earlier! Kaname tries to say hello, but is brushed off. The guy is Issei Tsubaki and he's the karate captain. He challenges Sousuke, who accepts. It's a showdown between Tsubaki and Sousuke. Tsubaki launches a Thrombotic Fist attack that levels Sousuke. Sousuke gets up and realizes he has to fight seriously. Tsubaki says some more words, and puts on his glasses. Then he sees and recognizes Kaname from before! As he is visually stunned by Kaname's presence, Tsubaki apologizes for his behavior the other day. Sousuke easily knocks Tsubaki down and wins the fight.
The dojo is demolished, and the Karate Club demand a rematch, which Sousuke agrees, much to Kaname's protests again.