Koi to Gunkan恋と軍艦 ; Love and a Warship

From Aerandria Scans: Endou Kana is a cheerful school girl who has a secret crush on... the mayor, Minato Kouichi, a perfect gentleman and well-liked leader of the post-war town. With the help of her friend Akira, she investigates him, until the trail leads her to an abandoned-looking house where a strange and scary foreigner lives. He and Kouichi seem to have some kind of relationship, but what is it? Kana's and Akira's take on that question are completely different and there's still a chance both of them are wrong!