A mysterious “observer” who is a collaborator of Parallel Flight, Inc. Exio is an Earthling from Sydney, Australia, and his full name is Exio Grant.

Ostensibly, he is a masseuse with a reputation for his excellent skills and gentle personality, but behind the scenes, he is a member of an underground organization that is working to complete a plan. He seems to harbor extraordinary hostility toward the “Broker”.

Even Melide, Yoshiori, and Monomasa, his closest allies, don’t know much about his true purpose.

However, everyone who is involved with him as a member of the underground organization knows that he knows more about the ambitions of the Broker than anyone else and is working to stop him.

Those who come into contact with his life and learn his true intentions will learn about the position of “observers” in this world, how they are treated, and even how “observers” were born.

Exio is a kaibutsu made from a human that is capable of being an "observer". His ability as an "observer" is a similar function that comes from being a kaibutsu, and his transformed form is merely the outer shell of a kaibutsu. Since his body remains almost human, he leaves combat to his Ido Replica, which is an alter-ego of his ego. Also, the frenzy he uses when performing a side kick is merely a repurposed ability that was originally for himself.

An experiment by an "intermediary". It was to see what would happen if the information sharing function of a kaibutsu was applied to someone who was capable of being an "observer" and had resistance to dimensional observation. As a result, Exio became the first individual that could withstand it. The reason why Exio was able to maintain his sanity as an individual amid the endless circulation of countless selves in parallel worlds, their senses, thoughts, and experiences, was largely due to the fact that he had acquired a way to intervene in his own thoughts and was able to continue to embrace the delusions he called dreams. In other words, it's about getting revenge on the "interveners" and protecting the heroes that he sees as his own.