This game takes place in the not-too-distant future, when tiny robots can time travel into the past to collect "NostalJunk;, odds and ends from everyday living and bring it back with them. It's always been the Curator's dream to open a NostalJunk museum. With Chibi-Robo's help, that dream could become a reality.
In the beginning, Chibi-Robo is in a small metal room, with a lighted red button in front of him. The player is supposed to then interact with the button. A trap door goes off in the floor, and Chibi-Robo falls through. The Curator and Telly are in the Curator's office, discussing where Chibi-Robo is. Chibi-Robo falls, and bumps off of the Curator's head, and lands on the desk. Telly asks if the two are alright. Then the Curator explains about what NostalJunk and silhouette film are.
- Chibi-Robo - He is the main character as the title implies.
- (Space Hunter) Drake Redcrest - Returns in his Japanese outfit.
- Chibi Tot - These happy-go-lucky little robots want to be a Chibi-Robo one day.
- Telly - This is not the original Telly Vision that was in Chibi-Robo!. He is Chibi Robo's helpful robo-advisor loaded with handy apps.
- Curator - A connoisseur of everyday objects who hopes to open a NostalJunk museum. Some might say he's a bit absent-minded. He is the owner of the player's Chibi-Robo.
- Super Geotron X - This collector’s edition model is an exact replica of the famous television robot Super Geotron X. Ultimate! Geotron!! Thunder!!!
- Miss Clayra - Miss Clayra teaches at the Chibi-tot kindergarten. Turns out she’s been moonlighting—working two jobs is tough!
- Ketschburg and Mostardin - Ketschburg is ketchup and Mostardin is mustard. These colorful condiments will add flavor to your day with their saucy banter.
- Joshy Bear - Affectionately known as JB, this aspiring teen idol wants to shine on the stage. For now, he’ll need to pay his dues with some dirty work.
- Laroque - A lion fountain statue of a greenhouse garden. He adores all kinds of flowers and treats the garden as his life.
- Squid Vicious - A mascot of a sushi bar.
- Moppi - A floating lion-like toy who loves racing. He has two older brothers.
- Smoglings - Mischievous little pollutants who previously appeared in Chibi-Robo! Park Patrol. They play pranks and cause mayhem in many numbers.
- Drake is wearing his Japanese outfit in all regional versions.
- Smoglings also reappear in the game in a side game.
- Telly was the name of the original Manager in Chibi-Robo!, and he is the new sleeker model shaped as a cell-phone.