Zegion

Zegion (ゼギオン) is an insect Monster that has been found, rescued and subsequently named by Rimuru in the Great Jura Forest.

Appearance
During his debut, Zegion appeared to be an extremely large beetle with characteristics of both stag beetles and rhinoceros beetles.

Later he evolved into a humanoid form that looks like a warrior clad in pitch-black exoskeleton with visible golden joints. A red-tipped, sword-like horn protrudes from his forehead. The exoskeleton took the form of Rimuru's preference.

Personality
Zegion usually has a calm and serious demeanor, speaking very few words. However, he is fiercely loyal to Rimuru and any words he interpreted as an insult to Rimuru would quickly anger him.

Demon Lord Attacks Arc
While strolling through the Great Jura Forest, Rimuru walked into Apito and Zegion, with the two of them heavily injured. At first Zegion didn't want Rimuru coming any closer, but Rimuru managed to convince them to let him help them. The two end up being rescued by Rimuru when he shared some of his Slime flesh and also named them.

Afterwards Zegion started constantly training to become stronger.

The Octagram Soars Brightly Arc
Apito and Zegion were still in the insect form, but they managed to become much stronger than before.