* The twins, Hikaru and Kaoru Hitachiin: They are the most playful and often tease Haruhi and the other members. Their mischievous nature comes from their close bond and desire to push boundaries.
* Kyoya Ootori: While often seen as the "brains" of the club, Kyoya enjoys manipulating situations and using his cunning to achieve his goals. He's not always outright "naughty," but his calculated actions can be seen as such.
* Tamaki Suoh: The club president is often impulsive and prone to dramatic outbursts. He's not malicious, but his actions can be considered "naughty" due to their unpredictability and tendency to cause chaos.
Ultimately, the "naughty" aspect depends on your interpretation. Each character has their own way of being mischievous, whether it's through playful pranks, strategic manipulation, or simply acting on their impulses. It's a part of their charm that makes the series so entertaining.