Mikakunin de Shinkoukei is a Manga/Manhwa/Manhua in english language, ROMANCE series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

This is a four-panel comedy manga about Kobeni Yonomori, who on her 16th birthday suddenly has a young man with little presence named Hakuya Mitsumine and his little sister Mashiro appear in front of her. It turns out that Hakuya is her fiancé, and Mashiro is her future sister-in-law. The three (and Kobeni's overprotective big sister Benio) start living together under the same roof, and hilarious happenings occur.