You're My Flame Beneath The Warn Summer Sun

After surviving a intense battle against the powerful male upper moon demon Akaza with irreparable damage to his right eye and a broken arm, young swordsman Kyojuro Rengoku retires from his role as the flame pillar and makes his way to the small mountaintop home of the Kamado family, getting there after several days of walking forward along a single pathway. When the Demon Slayer Corps learns of this after a month, its leader makes his way to the Kamado family's mountaintop home with a request for Kyojuro to bring the Kamado siblings with him to his family's home and take the oldest of the six siblings on as a student so she can eventually take his place as the flame pillar. As a result, Sumiko, who is sixteen, Nezuko, Takeo & Hanako, who are all fifteen, Shigeru, who is fourteen, and Rokuta, who is thirteen, spend the next five years fighting against demons at night to become stronger through each kill they make with Sumiko living in the Rengoku family's manor, Nezuko living with the love pillar Mitsuri Kanroji, Takeo and Hanako living with sisterly trio Kanae Kocho, Shinobu Kocho and Kanao Tsuyuri, Shigeru living with the wind pillars Sanemi Shinazugawa and Masachika Kumeno and Rokuta living with the serpent pillar Obanai Iguro. During these five years, the siblings eventually each find love with Sumiko and Kyojuro falling in love with one another soon after she takes his place as the flame pillar after a year and a half, Takeo falling in love with Kanao, young Thunder breathing user Zenitsu Agatsuma falling in love with Nezuko, Sanemi's younger brother Genya falling in love with Hanako and Shigeru and Rokuta falling in love with Sanemi and Genya's two younger sisters Sumi and Teiko three weeks after being introduced to them.