Beelzebub

A giant, misshapen fly-like insect who serves as the narrator of the story. She takes a human form in the secret ending to the game. Beelzebub's outfit when she transforms into her human form is very fly-themed, with fly-shaped buttons, earrings, bracelets, and a fly-shaped broach. The inside of her jacket also resembles the pattern of a fly's wings and they rise and flap when she's excited. Said word for word by her in the secret ending, right before she lists all her titles: The Sovereign of Pestilence, The Warden of Decay, The Mistress of Flies, and The Queen Crimson. Her hair is shaped like a fly's head, with the messy bits sticking out being rather like a fly's bristles, and her nervous gesture where she wipes sweat off her forehead and hands is based on the tendency of flies to wipe their heads and forelegs off regularly.