Senchi kara Kaettekita Takashi-kun. Futsuu ni Koukou Seikatsu wo Okuritai

The hero who saved the world from an alien invasion war, Takashi Shibusaki. This legendary warrior has one dream: To live a normal high school life. After the war ended, he was excited that this wish would be realized, and he immediately decided to return and live a quiet life in Japan. However, his comrade-in-arms from Northern Europe, Natalie, somehow ends up moving into Takashi’s house, claiming that they're going to live together...?

Everything is for a peaceful youth. Takashi, the most powerful warrior who wants to avoid love and fighting, will he be able to obtain the peace he wants?

(Source: Shufu to Seikatsu Sha, translated)