Soga Kugisaki is an ally to the Naruhata Vigilantes and a former Instant Villain. Soga is a tall, skinny young man with wild spiky turquoise hair, a short goatee, and notably inward-slanting yellow eyes with very small eyebrows. His front teeth are shown to be sharpened to the point, while his back teeth seem to just be regular molars. He wore a tank top with a sleeveless vest over the top, jeans, leather shoes, and a plaid shirt tied around his waist. He later wears a sleeveless vest, jeans, leather shoes, and a hat and trench coat that resembles that of Knuckleduster's, albeit brown instead of green. When he injects Trigger, his physique increases, his hair becomes pointier and he grows spikes on his back and arms. Later, after he is forcefully administered a Trigger overdose by Kuin Hachisuka, he transforms into a monstrous, human-sized porcupine. Soga has a cruel and violent personality, and likes to humiliate and attack people. This stems from the fact that he has been discriminated against due to his actions and his Quirk. He seems to think that everyone around him sees him as some sort of monster, and has developed a love of making other people suffer in place of him due to these circumstances. He shows some signs of mental instability, as shown when he sees everyone around him with a mocking, condescending smile, and laughing at him, no matter who they are and what they are actually doing, suggesting that he is unable to separate reality from his perception of the world. It is suggested that this perception of the world is what makes him so violent. In spite of these flaws, he shows solidarity with his friends, who are other people who have been looked down upon due to their Quirks. He shows a strong sense of loyalty and care towards them, such as when he went to face Kuin alone and warned her to leave his friends out of their conflict. He also is very defiant when he knows he is being played, totally trashing a selection of Trigger drugs because he refused to aid in Kuin's plan in any way. Ever since he was saved by the Naruhata Vigilantes from the murderous Stendhal, Soga changed for the better, and became a valuable ally to the Naruhata Vigilantes. As a result, Soga became somewhat of a vigilante himself, convincing and helping Koichi Haimawari to save Pop☆Step, even though it breaks many laws.