Mathias is the Leader of the Religious Organization which supports the Knights of the Silver Tree. It is revealed that he is a fake Leader that was only chosen for his unusual memory skills, because a new true leader hadn't been born at the time the previous leader died.
Mathias has long greenish blonde hair tied to a slightly loose side ponytail and light green eyes.
Mathias is shown to be kind and consedirate at first but in the Second Season, he kills the High Elder. He really loves the Holy City and refuses to leave causing him to do sinful actions. He then places an Artifact chip created by Erenfried on his neck to receive Purifying powers. Due to the chip, half of Mathias is controlled by a Thanatos. He is killed by Erebos when trying to protect Rene.
Mathias was chosen to become the next Religious Leader after the previous one passed away. To become the Religious Leader, he had to learn everything so he was told to read a lot of books. Mathias hesitates and complains that it's too much but then the High Elder explains that he can do it because he has
unusual memory skills. He finished reading the library of books in 7 years.