After starting a New Game +, Design Materials trading cards can be found in chests throughout the game, or buried in Santa Destroy. (A great deal of buried cards can be found on the beach, or in the field where Travis entered the Rank 5 battle.)
Extra health and power
As you approach the location of a boss battle, there are almost always two boxes nearby. One box will contain health, and the other a battery recharger. If you enter the nearby save room (or simply leave the area) and return to the location of the boxes, both will return, full of items for you to grab once more.
Fast travel
Tired of driving everywhere ? Select a mission from K-Entertainment. Then cancel the mission via the Side Jobs tab on the status menu. After cancelling the mission, Travis will appear at the very spot the mission would have started. You can also return to the No More Heroes motel instantly by driving the Schpeltiger into the river or off Iron Claw Point.
Hidden combo
When charging up your beam katana for the special attack, release the A button and then keep pressing it. Travis will perform a charged combo which does a lot of damage to regular enemies and bosses. This should help with defeating the secret boss.
Minigame
Beat the Rank 04 Battle to unlock "Pure White Giant Glastonbury" on your motel TV.
New game +
Beat the game, save, and load that save to begin a New Game +. In the new game you'll have all the money you in your previous playthrough in addition to all of the clothes you found and bought. All jobs and missions will be unlocked as well as some new shirts at Area 51.
True ending
To see the game's real, "true" ending, you must collect all of the game's Beam Katanas.
Very Sweet mode
Successfully complete the game. All female villains will be dressed scantily in this mode.
00 shirt...