Hold the corresponding key(s) while selecting the "Boss Rush" option to activate the corresponding modifier(s). You can activate more than one modifier at a time. If done correctly, you will hear a sound.
- Hold [C]: HP and WP refill after each battle
- Hold [I]: Nightmare difficulty
- Hold [N]: Ultimate Zangetsu (Full-Powered)
- Hold [T]: Infinite weapon points
Unlock the Nightmare and Ultimate difficulties to unlock Boss Rush mode, which gives you control of all four party members and a selection of their sub-weapons. In this mode, you will skip the levels and only fight all eight bosses. You need to defeat all eight bosses in a single run, without any continues or extra lives. All bosses are the Normal mode versions. Veteran mode is locked -- so you will be knocked back after taking damage. Your weapon points will be refilled after every boss. After each boss, you will teleport to a room with two large hearts and sub-weapons. These items do not respawn, so wait and use them later in the boss rush when you need them. Note: You can only equip one sub-weapon per character per fight, and Zangetsu does not have any of his special abilities from the "Bad ending" route.Nightmare mode
Successfully complete the game on the Normal difficulty to unlock the Nightmare difficulty. In Nightmare mode, you start with all three companions (Alfred, Gebel, and Miriam) unlocked, but without Zangetsu. The bosses are enhanced in this mode, and gain new special attacks. The last level is completely different, and you will fight a new final boss. Complete Nightmare mode to view the "True ending".Ultimate mode
While playing the game on the Normal difficulty, do not recruit any of the three companions when prompted. Instead, kill all of them (slash them a few times with your sword attack instead of pressing Up near them after the first three boss fights). Zangetsu will gain their souls and a special ability from each of them. Successfully complete the game this way to unlock the Ultimate difficulty. In this mode, you start with Zangetsu's special abilities (double jump, dash, and mid-air attack) and the opportunity to recruit the three companions. The bosses are also enhanced in this mode, with new attacks and more health.