We Love Katamari

Note: This game is also titled Minna Daisuki Katamari Damacy.

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

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

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

Million Roses level:
Successfully complete the cousin collecting level, then talk to the red rose in the back of the meadow.

After collecting one million roses, you will unlock alternate starting text, have roses appear at the level selection screen, get an alternate loading screen, and another Dokaka song.

Staff Credits level:
Successfully complete the game, then talk to the girl with the yellow shirt in the meadow. You can now 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, Complete the Roll Up The Sun level to unlock the introduction from the original Katamari Damacy. Complete the Roll Up The Cousins level to unlock the Hoshino family intermission sequences.

Comet show:
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.

Alternate title screen:
Successfully complete the game.
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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. They are cats meowing for the first file, cows mooing for the second, and chickens clucking for the third.
Ryan Sullivan.

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.

Comet storm/alternate cosmos perspective:
Earn 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.
alphachimp.

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.
Jennifer Jeremy.

Hint: 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.
Arananther.

Hint: Cousins 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.
Kenju.

Hint: Ignoring the King:
When playing one of the levels the King usually has a brief conversation with you at the beginning of the stage. You can skip this conversation by rolling. When you roll up an item the King will complain about being ignored.
Mathew Macaruso.

Hint: Original Katamari Damacy girl:
In the 1000 Paper Cranes level, in one of the hallways 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.
Kenju.