A brief summary of the endings. The Bad Ending is obtained by running out of time during the fight with White Reimu.
Ending 1
Bad Ending: Marisa fists herself. She dies of blood loss.
Ending 2
Good Ending 1: Marisa fists herself. She survives, if not unscathed.
Ending 3
Good Ending 2: Marisa fists Reimu. They both have a good time.