On the last day of the semester exams, after the rainy season ended and the heat set in, Yumi watched the members of the Sanbaihaku-kai gathered at the Rose Hall, feeling envious. This was because everyone had made plans to spend time together as sisters during the summer vacation. However, unexpectedly, Sachiko-san invited her to join her at a summer villa?! But one after another, uninvited guests appeared before the Hongjangmi sisters, who had intended to spend some quality time together! This is the 12th volume depicting the delightful summer vacation of the Hongjangmi sisters.