Like Resentful Heart, Mask prefers disguising his body with clothes. It has a cloak wide enough to cover three to four humans with all sorts of ornaments hanging all over. Upon closer inspection, it can be seen that it has bone knives, metal armors, and even a few screws.
Its arms are dry and long.
Its head can also be said to be extremely unique. It's shaped like a pillar with all sorts of masks hung all over.
Once it removes its masks from its head, however, an extremely grotesque appearance is revealed. More than 10 stacked heads—a mix of demons, humans, and other creatures—can be seen. Every single face has a different smile, and observers might find it to be very disturbing.
Nassaupelle often shows his contempt towards his fellow Demon Lords, since they seem to think that physical power is more important than understanding the inner workings of the world. He often said that in the face of knowledge, even the strongest physical body is nothing. He claims to be seeking knowledge and truth and to hate the most those born with extraordinary gifts. Also, he shows traits of megalomania, seeing himself as superior to everybody and wanting to own everything: "All emotions, experiences and knowledge shall belong to me".
Demonstrated by the magic power barrier protecting the Red Mist lake at the center of the Deity of Gods, Nassaupelle had succeeded in realizing the idea of "using a core apparatus to simulate the cyclone structure of the magic stone and amplify its result substantially". Although this idea came about a long time ago, there were many restrictions on it, and that Nassaupelle succeeded proves its intellectual and practical capabilities. His more than 10 heads serve a practical application, which is to increase his computing power and compatibility with their technology. Due to his many heads being able to rest independently, he didn't require long periods of rest and so he could mantain a long period of lucidity. 
Network of Mind
Mask was seemingly blind and slow with the Realm of Mind, only capable of establishing a connection with the Realm of Mind with the help of the Birth Tower. Later on, however, he is able to create his own "Realm of Mind" inside the demon network, by transplanting his mind into it.
After Ursrook's loss, nine demon lords gathered to discuss the situation at Western Front. In the end, Mask promised additional forces without affecting defences. However, it would cost a lot of God's Stones.
After his fight with Serakkas, he uploaded his consciousness into the demon network and claimed to be free of his original shell and no longer bound by rules, transcending everything. However, while on board the flying King's City he got killed with the deployment of the two "Glory of the Sun" in it.
- Chapter 1169
- Chapter 1384
- Chapter 1170
- Chapter 1409
- Chapter 1429
- Chapter 1436-1437
- Chapter 1411
- Chapter 1464
- Chapter 1403
- Chapter 1169-1171
- Chapter 1468