Ruby Crescent

O-Parts Hunter, features a cast of characters created by Seishi Kishimoto.

Jio Freed (ジオ フリード) is the twelve-year-old protagonist with great battle skill, an obsession with money and is not soon to show his feelings, often hiding them or blaming other factors. Jio started his life without friends. The people in his village forced him to leave after the death of his only friend's, Jin, parents for which he was blamed. He was trained in the wild by a wolf, known as Zero. However, after completing his training he was chased away again, giving him a chance to complete his dream of world domination.

He meets Ruby Crescent, a girl in search of her father, and agrees to help her as a paid bodyguard. She ends up fighting a man claiming to be Satan, but the real Satan (sealed inside of Jio) easily beats him after Jio is knocked out. From there, he says he will follow her until she can pay him for saving her. He claims, in front of her, that he is only her bodyguard and nothing more; but Jio sees Ruby as a precious friend and appears to have a crush on her. Later on, he says that he was Ruby's lover and wanted to be near her.

After gaining Ruby and Ball as friends, Jio becomes more trustful of people and slowly breaks away from his dream of world domination, choosing to be more helpful and caring of others. This new outlook quickly gains more friends. He meets Mr. Wick and Mrs. Basil, who he sees as his father and mother, never having known his real parents. He was emotionally crushed when they were killed by Kujaku in cold blood.

In Rock Bird, Jio is defeated by Anna in the preliminaries, but the officials allowed him to move up due to the demon inside of him. After Jio's last fight, Satan begins to awaken but Ruby calms him. This leads to Rock Bird's leader dubbing Ruby his 'Key' and kidnaping her. An enraged Jio with Ball following his lead, runs to the top of Rock Bird to rescue her. Jio defeats the leader, who was also a demon, but not before Satan takes control of Jio's body. Shin shoots a laser which causes a form of death by forcing all souls to leave their bodies. For Satan to survive, he absorbs Ruby's soul and Ruby releases Jio. Ruby stays inside of Jio to protect him against Satan's control.

A time-skip to years later shows Jio has become the leader of the cyclops village, setting up a successful trade and supply route, and sending 'some early cash' so that the village can survive. He is discovered by Ball and rejoins his group to rescue Ruby, as well as stop new threats. During the assault on the Stea republic to rescue Ruby, everyone was split up in battle. After being reunited with his group, Jio was relieved that Cross and Mei were all right but Jio didn't seem to notice Ball, possibly as he feels Ball can take care of himself. After rescuing Ruby, Jio holds a conversation with her atop their ship, asking her out.

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