It's been six years since Hiroshi graduated from high school, and now he's back at his old stomping grounds, an aquarium in the shopping district of Toranomachi. He's glad to be back, because it's a place he used to go to when he was a kid. He tells us that the aquarium will be closing down in the future, but that he'll still be able to visit it because he was there when he went to school. He reminisces about his high school days, and how he was always unsatisfied with his romantic life. One day, he spotted a friend of his cheating on her, and the two of them ended up breaking up. Then there was another guy who he kept missing, because he didn't have a job. And then there was a third guy who was also missing, but he had maybe just had a job, so they just kept breaking things off. Hiroshi wonders if his friend's love life is going well, and he worries that if he changes the past, then his future will also change. If he makes a mistake, he could end up ruining the man's life.