Summer breaks can be boring if you don't have a summer job, internship, or anything exciting going on. But what if one encounter can change all of that? Mirai is spending her last summer at home before graduating from college. Like every summer, she lies lifelessly on her bed waiting for something to make her boring summer go by faster. Her wish is granted when a mysterious person shows up in her room! Before she knows it, she's thrown into a crazy time-traveling adventure that changes her life. Who's this person and what's his purpose?