Finish the game on the Hard difficulty setting while using no continues. Following the ending credits, save the game to a memory card, then start a new game. At the Fighter Selection screen, if you cycle through the ships, you'll find a new craft: an Unknown Fighter Type II, called the Selene. This new ship can carry 9999 rounds of ammo for any weapon it gets during the game.
Secret Area and Flash Weapon
Secret Area: In Stage 1, satisfy the following conditions to access a secret area:
Flash Weapon: In Stage 3, satisfy the following conditions and the Flash weapon should fall from above: