Bismarck

"Fantastical paintings decorated the walls, but were they really paintings? The phantasmal creatures, which appeared to have been painted with an elaborate touch, changed their posture from time to time as if they were alive. It felt like they could pass through the canvas and emerge into the real world at any moment. And It is no wonder. These paintings were created by Bismarck, a master of the monster world. They are artifacts called "sealed paintings," which are said to have sealed up the beasts while they were still alive - artworks of the most sublime quality."

Bismarck (ビスマルク) is a legendary artist, said to be one of the finest masters in the realm of monsters. They're most famous for creating paintings of phantasmal beasts, which are actually magical artifacts called Sealed Paintings (描封画) that trapped their still alive spirits inside. A single one of these paintings is said to be worth so much money, that someone could live every day as lavishly as possible for over ten years. They were known to provide their services mainly to Demon Lords, most notably to the Demon Lord Clayman.