Sayonara, Watashitachi ni Yasashikunakatta, Subete no Hitobito

The young woman devoted her existence to avenging the seven individuals responsible for her sister's demise. Akada Town is a rural locale encircled by mountains. Shiori Nakagawa, a high schooler residing in this area, had ceased attending school due to harassment. One day, a girl named Mei Satou arrives to live with Shiori as her roommate. Mei, who is closed off to others, divulges her reason for coming to this town only to Shiori. “I am determined to take the lives of the seven people who led my sister to her end.” Three years prior, Mei’s sister Akari endured severe bullying in this town and chose to end her life. Mei has returned to seek vengeance. She intends to carry out the blood-drenched ritual known as 'Okakashitsutsumi,' a tradition passed down at Akada Shrine, to manifest the large serpent deity 'Okakashisama' and eliminate all seven persons involved. On the evening of the summer solstice, Mei successfully completes the ritual. From that moment on, empowered by the god and alongside Shiori, Mei embarks on a quest to eliminate those responsible for her sister’s suffering, systematically killing them one by one each day. Amid their journey of retribution and evasion, the pair gradually form romantic feelings for one another. Nevertheless, Mei harbors a crucial secret from Shiori: anyone who performs the 'Okakashitsutsumi' is ultimately required to sacrifice their soul to the deity, signifying that Mei’s own demise is unavoidable.