Shuumatsu no Waltz

A scientist named Shirou lives in a world on the brink of destruction, dedicating his life to developing butterflies capable of cleansing the environment. He meets a humanoid figure named Kuroe, who expresses a desire to see him. The nature of Kuroe’s true self and his reasons for seeking Shirou remain unclear. The two form a deep connection as they navigate the final days of their dying world.