Goichi Otonashi is a significant character introduced in the second season of the narrative. He is the elderly and wealthy chairman of the Otonashi Group, a successful international hotel and hospitality chain. His background is notably humble, as he was not born into the family but was originally an employee who offered management suggestions at one of the company's hotels. The then-president, Denjiro Otonashi, recognized his talent and had him marry his daughter, Sumi, bringing him into the family business.

Goichi's personal history is defined by a dark and pivotal event: the murder of his wife, Sumi. As detailed in the story, Sumi was a ferocious and controlling businesswoman who, after inheriting the company, drove it toward financial ruin while also dictating the lives of their three children, preventing them from pursuing their own dreams. Feeling powerless to stop her through conventional means, a desperate Goichi secluded himself in a mountain villa and made a pact with a fox ayakashi named Fubuki. In exchange for acquiring and developing a specific mountain, the spirit agreed to kill Sumi. Within ten days, she was murdered by an unknown assailant, and Goichi assumed the presidency. He went on to restore the company's finances and allowed his children the freedom to live their own lives.

In terms of personality, Goichi is presented as a shrewd and pragmatic individual, capable of making a calculated and morally grave decision to eliminate his wife for the perceived greater good of his family and company. Despite this cold calculation, he is not devoid of conscience. Years later, having been diagnosed with cancer and given about a year to live, he is consumed by guilt and a desire for accountability. He does not seek to escape punishment but rather wants his three adult children to know and believe that he was responsible for their mother's death. His motivation is to ensure they understand that resorting to supernatural means to solve one's problems carries a grave moral weight and is not an action to be repeated.

Goichi's role in the story is that of a client who seeks the unique services of Kotoko Iwanaga, the god of wisdom who mediates between the human and supernatural worlds. Knowing that his children would never believe a simple confession from him, especially given his strong alibi at the time of the murder, he devises an unusual plan. He tasks Kotoko with overseeing a process where he informs his children of his guilt and then challenges them to come up with their own logical theories for how he could have committed the crime, promising a portion of his inheritance as a prize for the best explanation. His relationship with Kotoko is one of mutual respect; he acknowledges her unique position and intellect, calling on her to not only help craft a believable truth but also to ensure that the supernatural order is maintained, as Fubuki was punished by his own kind for the killing.

Throughout his brief but focused appearance, Goichi demonstrates notable abilities, primarily his exceptional business acumen that allowed him to rise from an employee to the head of a global empire. More uniquely, he possesses a strategic and manipulative intelligence, evidenced by the inventive way he chooses to confess his crime. His development is not about a change in personality but a revelation of its true depth. He transitions from a man who secretly committed a terrible act for practical reasons to an elderly figure seeking a form of atonement and a final lesson for his children, hoping to ensure his sins are not repeated after his death.