It is recommended to watch the 2 OVA episodes first. There is not much change in the content of the story. In this movie they spend longer on land because there is a festival at their school, it can be said that the story tells more about their fun during the festival. However there is a bit of personal conflict between the captain and vice captain of this Harekaze Ship. Even so in this movie, the war scenes are also good, even in my opinion this is the most tense compared to the anime series. I hope there is a sequel to the series.