Myoshin Ono founded the religious group Bettenou, which became notorious for follower deaths occurring when families expressed doubts. Bettenou's power manifested perceived realities through spoken words, enabling these fatal outcomes.

Before founding Bettenou, Ono belonged to the volunteer group Singing on the Battlefield alongside Yuuko Kurata, Tatsuya Yamaga, Yasuo Saburi, and Kumi Yasuda. While traveling through a war zone, their vehicle crashed. Shinjūrō rescued them from the burning wreck, but an explosion severely injured him, triggering the awakening of Inga. Inga consumed the souls of several group members. Ono emerged as the sole initial survivor and returned to Japan alone.

Upon returning, Ono seemingly led Bettenou's activities centered on its abilities. However, the cult leader was later revealed to be Makiro Serada, another Singing on the Battlefield member and Japan Self-Defense Forces operative, impersonating Ono. Serada used Bettenou's power to manipulate perceptions, making followers believe he was Ono. Dental records confirmed the impersonation, proving the real Ono died during the war-zone incident. Serada exploited Bettenou to establish the cult, control narratives, and eliminate skeptical followers.

Ono's actual fate was death during the Singing on the Battlefield mission. Recovered footage showed the group's execution, though Bettenou's influence obscured this truth. Serada utilized Ono's identity to maintain control over Bettenou and the cult, leveraging the deity's power to enforce his authority and conceal his actions.