Mikimoto Isao is a member of the Galients, a band of former convicts surviving in a post-apocalyptic world. Before the global crisis, he was an Olympic pole vaulter, an athletic background that directly shaped his method of combat.

He has a slim physique, black hair typically tied back, and a large red earring on his right ear. He wears a shirt featuring a skull design.

His personality shows sympathy and respect for certain individuals, particularly Renjiro Hatonami and Guren Soshigaya, due to their display of manhood. This admiration forged his loyalty to them and the Galients group.

After the outbreak, he was imprisoned. He escaped when the jail was attacked by creatures called Gibia and later joined Renjiro's group.

Within the group, he participates in supply missions. During a food shortage, the Galients captured a member of another survivor group to demand supplies. He was present when Renjiro Hatonami was easily defeated by the samurai Sensui Kanzaki, after which the Galients retreated with their leader.

He also joined a subsequent attempt to ambush the same group, an encounter interrupted by the attack of a powerful Meteora creature. During this conflict, the Galients were ultimately saved by the intervention of Sensui Kanzaki's group.

Using his past expertise, he designed a unique spear that functions as both a weapon and a mobility tool. He uses it offensively to stab and kill Gibia monsters and defensively to launch himself high into the air, mimicking his former pole vaulting skills.

The name Isao means "that one," "help, aid," and "man, husband." His surname, Mikimoto, means "beautiful," "tree," and "base, root, origin, source."