Collect all trophies in the museum (i.e. 100% completion of everything in the game). Then, successfully complete the game again, and wait until the end of the "Staff Credits" sequence. The screen will cut back to the Origami Castle display featured near the end of the Origami Festival sequence, and will zoom in on the empty origami chairs sitting atop the origami castle. The Origami Master toad will suddenly walk in from the right side of the screen, and stop in front of the origami castle. He will then turn around towards the origami castle, and add two items to the display. Once the Origami Master toad is finished, he will walk off screen to the right, and it will be revealed that the two items added to the display were actually miniature origami versions of King Olly and Olivia (both seated in their respective origami chairs).
Secret endgame banners:
There are two secret achievements the game does not display but records. If either of these are accomplished, a corresponding banner will appear in the ending picture in the credits. Note: The game does not count either of these achievements towards 100%.
Gold fist banner: Successfully complete the game without equipping battle accessories.
Gold heart banner: Successfully complete the game without getting a "Game Over."
Trophies are special items Mario can unlock by completing difficult challenges throughout the game and by unlocking everything inside the Musee Champignon. After unlocking a trophy, Mario can talk to the Toad inside the Museum to add it to the Trophies Collection inside the Treasure Gallery. Successfully complete the indicated task to unlock the corresponding trophy:
Art Collector: Unlocking everything in the Art Gallery.
Battle King: Win 200 battles.
Coin Collector: Collect 300,000 total coins (not affected by spending them).
Collectible Collector: Obtain every Collectible Treasure in the game.
Origami Aficionado: Unlock everything in the Origami Character Gallery.
Origami Toad Collector: Unlock everything in the Origami Toad Gallery.
Ring Champion: Defeat all seven Paper Macho Bosses in a row on Scuffle Island.
Shuriken Master: Get at least 100 points in the Shuriken Dojo's Expert mode.
Sound Disc Collector: Unlock everything in the Sound Gallery.