He is the Tower's 4th master and seems to have a connection to Opion's Master's past. He seemed to have let Master off the hook for something but this has yet to be revealed. He is also the one person who wants the [Door] to open, despite the safety of everyone being in potential danger.
He is the First Tower's Master. He also has the same name as the founder of the tower, but as hint by Mikelcarugo, they are not exactly the same. Meredith also has a piece of the Demon King (brother)'s memories.
Yumehen is a prince within the Imperial City. He is the younger brother of the Crown Prince and the older brother of Yutiarien Meria Kansiole. It's also implied that he has a connection to Lanoste and Shicmuon, as he knows Shicmuon's real name and identity. Yumehen has a calm personality, but he doesn't hesitate to get himself involved, if necessary. Thus, he agrees to help Shicmuon, seeking into the tower. Also Yumehen wanted to send magicians to the tower, when this was in trouble. Due to his lack of talent for magic, he is not able to hold the Mark Of The First Contract.