Juuou Mujin no Fafnir

Second Lieutenant Yuu Mononobe is assigned to Midgard, an all-girls school where his sister Mitsuki serves as student council president. The institution trains individuals with "D" powers, necessary for battling dragons, a category that includes both Yuu and Mitsuki. Upon arriving, Yuu meets Iris Freya, a classmate struggling with her "D"-related studies. The two form a friendship and work together to navigate the challenges of their environment.