As part of the Dark Cloud race, he lives in the Abyss under the rule of the Demon King, Barbatoy.
Galkima is the first Dark Cloud to appear in the story. He appeared in the Orange Zone when Elkadion accidentally transported his soul from the Abyss into the body of a human when using the Soul Telautograph. His strength vastly exceeds that of every resident of the Orange Zone, including Hansoo's, even though he is currently only able to manifest 0.5% of his original power, due to the weak body he is controlling. If he were to control Elkadion's body, which is comparable to Hansoo's, he would be able to use up to 5% of his strength.
When Galkima first came to the Orange zone he takes over the Akadus and tries to consume everyone and follow the zones up to kill all the humans. With the efforts of Hansoo's team and knowledge from the future they eventually defeat him.
After Hansoo and the rest of the people from the Orange zone finish defeating Galkima the fairy gives the humans who fought the Dark cloud race the ability to control a dark cloud themselves. The amount of the cloud was directly proportional to the amount the person destroyed. In the Yellow zone Hansoo uses this ability multiple times and is unknown how many people now have this new ability. It is believed that the while Hansoo is clearing the Yellow zone the inhabitants who are in the orange zone are mastering the Dark Cloud ability.
He is able to control a vast number of beings, by using Dark Clouds, which he also refers to as, "clones". He had enough defense to only gain scratches during his battle with Hansoo while using only 5% of his strength.