Dark Elf no Mori to Nare: Gendai Tensei Sensou

Asakura Rensuke is a skilled pilot of an Iron Steel Knight, tasked with defending Japan from creatures known as Radiant Beasts. He is also a high-achieving student concealing his duties. One day, while in a tree, he is surprised by Sheena, a dark elf and high school student who claims to have been reborn from another world. Sheena exhibits a flirtatious manner, bold behavior, and a cheerful demeanor. Rensuke takes her in as a member of his household, and they begin living together. They soon become entangled in a struggle for survival among various magical beings who have also been reborn from other worlds. The two find themselves caught in a conflict that threatens their existence.