Secret Plane: The Black And Red Shinden
After beating the game on Wing King difficulty setting, go to Shinden in the plane selection screen and select it by pressing "Y" to use a black and red version of the Shinden with maxed out power.
Red And Black Shinden
Successfully complete the game under the Wing King difficulty setting. Highlight the Shinden at the plane selection screen and press Triangle. You will now have a red and black Shinden with maximum power.