Yasuji Kumagaya, the deceased grandfather of Kosuke Kumagaya, lived in the same apartment complex for sixty years until his death. This complex held deep personal and familial significance, serving as the shared childhood home for both Kosuke and Natsume Tonai. His passing coincided with the scheduled demolition of the building. Yasuji regarded Natsume Tonai as his own granddaughter, demonstrating a close familial bond despite their lack of blood relation. His death contributed to growing tension in the previously sibling-like relationship between Kosuke and Natsume, influencing their interactions afterward. One of Yasuji's known personal interests was photography. His presence and influence persist within the narrative through memories and the lingering emotional impact on Kosuke and Natsume, especially concerning their shared history within the soon-to-be-demolished apartment. Information regarding Yasuji Kumagaya is derived exclusively from the 2022 film.