Haikara Otome: Kaika Sengen

The one who proposed to me is a mafia boss!? It is the age of Westernization during the Meiji era. Asuka Haruomi, the daughter of a trading merchant, is being attacked on the street, when she is rescued by Gil, a blonde-haired, blue-eyed foreigner. Suddenly, having fallen in love at first sight, he proposes to her, but believe it or not, he is a mafia boss...?

(Source: Shogakukan, translated)

Included one-shots:
Volume 1: Tsumetakute Attakai.
Volume 2: Kono En, Zannen Nagara.