On the fifth day of Golden Week in Japan, Setsuka spends his vacation hanging out with her best friend, Kaede. Of course, they weren't alone because there was a little girl among them. That person is Kohana, the younger sister of Setsuka.
When Kohana finds out that her sister is going to hang out with Kaede, she begs to join them because she's bored of staying home for the holidays.
Originally, Setsuka had refused her little sister's request because she had something she wanted to talk about with Kaede alone. But then Kohana burst into tears, and her parents asked Setsuka to take her. Thus, she reluctantly agreed and brought her little sister along with them.
Kohana and Setsuka left in the morning and promised to meet with Kaede in the middle of town. The first place they will visit is an amusement park. Kohana insists on playing there, and neither of them can refuse. Setsuka and Kaede quickly agreed because they didn't want that little girl to whine in front of so many people.