"Remember, only a regular battle will let you collect a debtor's soul contract. Now scram!"
—King Dice, after you first beat a boss on Simple Mode.
Regular mode is, as the name implies, is the normal mode you are intended to play on. Bosses have all their phases in this mode. It is required to play each boss in this mode to complete the main game.
Top grade: A+
On this mode bosses have less phases, easier attacks, and have a certain pattern to follow (ex: Cagney Carnation will first use lunge attacks, then the gattling gun, followed by the "magic hands" attack, and ending with the gattling gun.). Bosses also use less projectiles at times, for example, if a boss fires 4 bullets it will instead fire 3 bullets instead. You will not earn any soul contracts in this mode if you defeat a boss.
Top grade: B+
This mode is only unlockable once you beat The Devil in One Hell Of A Time. All bosses have more health, and more attacks (ex: If a boss fires 4 bullets it will instead fire 5.). Beating every boss in this mode will give you the achievement "Beat The Devil At His Own Game". A golden flag with a gold cup on it will appear when you beat a boss on this.
Top grade: S