Tayuma Shijima was the head of the Shijima clan. He was one of the major members of the Radical Faction of the Underground People, being second in command. This made him a major antagonist of the story before his final defeat and death.
Tayuma was a headstrong, highly prideful and powerful man with great influence to the many weapon makers of the Underground People. His pride is what lead him to reject the Conservative's Faction of peacefully migrating to the surface overtime without the notice of the Surface dwellers - thinking that this method is far below him and that this would leave the Underground People's cultural identity to be in shambles. He even arrogantly believed that everything he did was right and that justice was on the Radical Faction side. Even both Maya and Elexis were disgusted by Tayuma's method.
Although he holds considerable amount of power within the Radical Faction, he is not actually the leader of the Radical Faction. He is however, able to approve of allying with people like Maya as he argues that she was technically a part of the 7th clan of the Underground People. However, this stubborn nature would be the cause of his downfalls later on in the story.
Tayuma was often compared to dog: being completely loyal to his master Maguz, was quick to bark and bite at anyone who angered him in the slightest, but would pull back when order to. He was a least a aware of this comparison as well, as the form he took after absorbing the energy from the destroyed Earth Dragon ended up resembling a hunting hound.
Powers & Abilities
Coming from a long line of warriors, Tayuma was a highly skilled swordsman himself. During his battle with Koutaro Satomi in Volume 16, Tayuma used armor that was enhanced using both spiritual energy technology and magic. Using this armor and his swordsmanship, he could fight on equal footing with Koutaro while he was using his Blue Knight armor.
During the final battle, Maya transfer the energy from the destroyed Earth Dragon into him. While in the middle of transforming, Tayuma began to summon power from a higher dimension due to his lust for power and hatred. He temporary transformed into a monstrous hound that dwarf even the Fire Dragon Emperor Alunaya in size and power. He was protected by powerful barriers that were able to reflected the bombardment from the Blue Knight spaceship right back to it.