Scheduled for routine military exercises, Commander Kadomatsu and the crew of Japan's newest and most modern Battlecruiser, The Mirai, are ready to test out the ship's state-of-the-art Aegis System. Instead, they find themselves transported back to June 4th, 1942—date of the crucial Battle of Midway, where the Japanese fleet was dealt a crippling blow. When an overzealous Kadomatsu rescues one of the battle's victims, Kusaka, from a sinking zero fighter, the Mirai's fate is sealed. The crew pledges not to do anything to alter the past further. However, they're now forced to fight a U.S. submarine in a battle that should never have occurred. Thus setting off a chain of events that may forever change the flow of history!