Shuriken School/YMMV

Canon Sue: The cheerleaders Torrance, Missy, and Casey in "Cherry on the Cake". Upon their arrival, nearly every male student becomes infatuated with them. They are able to master a complex fighting technique in the span of a day and are able to easily take down Naginata and his boys despite the latter group being subjected to rigorous training at Katana.
Draco in Leather Pants: Naginata fits this to a T, being a clear-cut example of Ensemble Darkhorse. The other students of Katana to a lesser extent.
Evil Is Cool: The Katana School studentss are clearly this, especially Naginata, who doubles as Evil Is Sexy in the eyes of the fandom.
Foe Yay: Eizan and Naginata. So very much.
- To a smaller degree, Jimmy and Bruce.
Jerkass Woobie: Daisuke in "Okuni for President". Despite him being an egotistical Casanova Wannabe, it's hard not to pity him when he gets depressed for failing to win Ami's heart. He even joins in Jimmy and Pork's Snowball Lie just to get her attention. He gets even more pitiable in "The Old Master", when he actually cries when he thinks she likes Jimmy instead of him.
- Okuni, Jimmy and Vlad also have their moments.
The Scrappy: Kazumi, In-Universe and out.
Toy Ship: Eizan and Okuni. Being kinda canon definitely helps.
- Also Naginata and Ami, being one of the most popular ships. Doubles as Angel-Devil Shipping.
The Woobie: Eizan. He's basically the series' Butt Monkey.
- Marcos even more so. He has been running away from the shady wrestler group "Los Tres Santos" since he was a kid. It gets worse in "An XXL Lie", when it turns out Los Tres Santos weren't pursuing him at all, and he simply misunderstood the events, making his runaway status pointless. And if that wasn't enough, when he thinks Los Tres Santos had discovered his hideout (he was deceived by Jimmy and Pork's lie), he tries to leave Shuriken out of fear. Poor kid needs a hug.