Executive Director Yūichirō Kaidō is a 67-year-old male who serves as the Secretary-General of the organization known as Coulomb's. He is a calm and composed individual, acting as the collected leader of the group. Known for his pleasant personality, Kaidō has earned the deep trust and respect of the researchers working under him. He also has the responsibility of presiding over the regular report meetings held by the organization.

Kaidō is a widower; his wife, Etsuko, is deceased. She was a research assistant to the renowned Dr. Shinosuke Mishirashi. Following her death, Kaidō inherited her dream of creating a world where monsters and humanity can coexist. This profound personal loss is the driving motivation behind his strong will and leadership, as he is dedicated to making that vision a reality. He is also described as a close ally, almost a sworn friend, of Dr. Chōji Kobayashimaru. His personal life includes having a daughter and a small dog as a pet. His favorite food is soba noodles, and his hobbies include playing go and shogi.

Information regarding his specific character development throughout the story or any notable abilities he may possess is not available.