B6 Comics Skyrockets, from below or from the side? (1)

Product description ※Please note that product information is not in full comprehensive meaning because of the machine translation.

Summer vacation is in a seaside town. It is a school day for a fireworks display. 典道 and Yusuke meet up in the swimming pool in the school with a idol of a class that they secretly love. Together with Nazuna, they will be competing in a 50-meter swimming race. 典道 fails to make a underwater turn and is defeated by Yusuke. On the other hand, Yusuke, who made the first goal, is invited to a fireworks display. 「 If I had won in the swimming pool at that time, I would have moved 」. When 典道 threw the balls I had picked up in the swimming pool, I realized that 典道 was again in the swimming race with Yusuke. What is the fate of Nazuna and 典道 to arrive at the end of the same day?