Amagami-san Chi no Enmusubi

From Kodansha: Uryu Kamihate has had a rough start to life but plans to forget it all by achieving his dream matriculating into medical school. But when he arrives at his new foster home, a working shrine, his dream of a quiet place to study goes up in smoke. Not only will he be living with the three beautiful, lively Amagami sisters but he learns that he must marry one of them and take over the shrine!