Complete the following requirements to unlock new ships
Unlockable Ship: Orchid - Complete Stage 5 (any) Using Tigerschwert
Unlockable Ship: Tigerschwert - Complete Stage 5 (any)
First, unlock stage 5E (you don't have to beat it), then turn on easy mode again and enter the level select screen. Despite easy mode normally being limited to A-grade stages, 5E can now be played as well. It's not the same as normal mode's stage 5E, however, but a hidden bonus stage.