The Kasai Yōsei are tiny messenger demons often used by Hadagi and Panti. Never more than 12 inches tall, they are often mistaken as dolls or action figures by humans on the rare occasion they venture out of Hell.
A hybrid of demon and fairy, the Kasai Yōsei have long, skinny bat wings for ears, which they use to hover and fly around. They have a thin, translucent skin, which does little to conceal their fiery innards. Their hands and feet are usually in waves and curls, and each carries an iron staff, topped with a red ball of fire.
The Kasai Yōsei can conjure up illusions. They can cast images of things they have seen, or on command, can produce an image of another demon's plan. When they cast an illusion, their black eyes turn sapphire blue. The flame on their staffs becomes sky blue, and they draw the images in blue smoke in the form of a circle. They rarely act of their own accord, often obeying the command of a more powerful demon.
Kasai Yōsei are very clean demons, often bathing between illusions. There are several ponds in Hell where you can find the sprites carefully washing every lock of their black hair. They do not speak, having no mouths and no vocal cords, so they communicate via illusions.
If you smell sweetened, burning leaves, but can see no smoke or evidence of a fire anywhere, it's a Kasai Yōsei spying on you.