Marnie is a student at UA with long blue hair that covers her shoulders and bangs that cover one eye. Her eyes are yellow and appear tired due to her quirk, and her teeth are sharp, but she's actually very shy and considerate, always carrying around antidotes to her poisons. Her quirk, 'Poison Counter', activates when she's scared or startled, causing poisonous spikes to come out of her hair that can cause dizziness or paralysis.