Rikako Muto's father lives in Tokyo after divorcing her mother. This divorce caused Rikako to move to Kochi with her mother and younger brother, though she resided separately from them. His absence from her life fueled significant resentment, particularly as Rikako had previously sided with him during parental conflicts and maintained an idealized image of their relationship. During a Tokyo trip funded by borrowed money, Rikako visited him unexpectedly, hoping to reconnect. She discovered him preparing for a trip with his new girlfriend, shattering her idealized perception. He appeared surprised by her unannounced arrival but responded pragmatically, reimbursing Taku Morisaki the borrowed funds and arranging Taku's accommodation at the Hyatt Regency hotel. Afterward, Rikako expressed deep disappointment to Taku, confiding her sense of betrayal upon realizing her father had moved on romantically, no longer matching her expectations. This realization fundamentally altered her view, transforming him from a figure of loyalty into a symbol of familial breakdown, further emphasized by his decision to remodel her former bedroom. He exhibits polite yet distant behavior during their brief interaction, primarily reacting to Rikako's arrival. His actions demonstrate a practical desire to resolve the immediate situation by addressing the financial obligation and providing lodging, simultaneously underscoring the emotional distance developed since the divorce. Rikako subsequently harbored lasting resentment towards both her father and his new partner. No significant character development or expanded background for him is presented beyond these events within the film's narrative or its source material. His role remains defined by his impact on Rikako's emotional state stemming from the divorce and her disillusioning visit. Later media, such as the novel sequel "I Can Hear the Sea II: Because There Is Love," do not provide additional exploration of his character or subsequent relationship with Rikako.