Original Katamari Damacy constellations
Have a saved game file Katamari Damacy on your memory card to unlock an option at the data screen that will allow you to import your constellations from the original game.

Memorial option
Successfully complete the game to unlock the "Memorial" option. Select it to access the game's music and movies.

Cousin Collecting level
Find all the cousins, then talk to the boy with the yellow shirt to play the Cousin Collecting level.

Million Roses level
Successfully complete the Cousin Collecting level, then talk to the red rose in the back of the meadow to play the Million Roses level. Collect one million roses to unlock alternate starting text, an alternate loading screen, another Dokaka song, and have roses appear at the level selection screen.

Save The Earth level
Successfully complete the game, then talk to the astronaut to play the Save The Earth level.

Staff Credits level
Successfully complete the game, then talk to the girl with the yellow shirt in the meadow to replay the level that featured the game's credits.

Bonus movies
Successfully complete the Cousin Collecting level to unlock a second bonus movie. In the PAL version of the game, successfully complete the Roll Up The Sun level to unlock the introduction from the original Katamari Damacy. Successfully complete the Roll Up The Cousins level to unlock the Hoshino family intermission sequences.

Comet show
Successfully complete levels in the game with a good time until all the comets are unlocked. When a comet is unlocked, it will streak through the sky and a button will be indicated. Fly into the sky from the hub screens to reach the Cosmos screen. Press the button shown earlier to see that comet again.

Comet storm/alternate cosmos perspective
Get all the comets, then visit the Cosmos screen. Press the corresponding buttons to "shoot" all the comets (the order does not matter). You will see a comet storm followed by a shift in perspective. This new perspective displays the cosmos as two perpendicular orbits.

Alternate title screen
Successfully complete the game to alternate the title screen.

Alternate start up sounds
Depending on which file you choose at the load screen, "Na", "M", or "Co", you will get a different start up sound. It is cats meowing for the first file, cows mooing for the second, and chickens clucking for the third.

Control loading screen
You can move the King's head to see what he is saying on the loading screens by pressing the Analog-sticks in the direction you wish him to move.

Getting cousins to follow
Hold Circle and walk by any cousins to have them follow you. They will even go from screen to screen. You can get all cousins to follow you.

Original Katamari Damacy girl
In one of the hallways in the 1,000 Paper Cranes level is the little girl from the original Katamari Damacy. If your Katamari is big enough, bump into her to hear her say, "Oh, I feel it," which was one of her famous lines from when you restored a constellation in the game.

Hear item sounds
When viewing collected items, press Circle to hear the sound made by that item when it is picked up. This is especially amusing with the people that are collected.