Kingyoya-san no Karisome Fuufu

The story of a contract marriage set in an old-fashioned goldfish shop. The story begins when Asahi comes to Shichi, who has taken over his grandmother's goldfish shop, and asks him, "It may sound rude to say this the first time we meet, but will you marry me?"

(Source: Natalie, translated)

Note: Includes one extra chapter.