Tenran no Natsu

Right before summer vacation the protagonist, who is enjoying his single life in Tokyo, is asked by his mother to return home. His father is in the hospital, and she wants him to run the family hot spring resort for a month until he is released.

His dreams of spending his summer working part time and playing around have been completely destroyed... or so he thought. But it turns out his home town is filled with cute girls who've been waiting to see him!

[Translation of synopsis from Getchu.com]