Geno's History
When the Smithy Gang launch their attack on Mario's world, Exor crashes into Bowser's Keep and occupies it. As Exor fell from the sky, he shattered the Star Road, and as a result, seven Star Pieces are scattered throughout the world, and wishes are unable to be granted. Because of this, Geno is sent to retrieve the Star Pieces and restore the power of wishes to the world.
Some time later, Rose Town is besieged by the Smithy Gang. Bowyer is launching arrows into the town and paralyzing people. Many people in Rose Town fear leaving their homes out of potentially being paralyzed by one of Bowyer's arrows.
During this time of crisis, Mario and Mallow arrive in Rose Town. The pair enters the Town Inn, and while inside, Mario sees a young boy named Gaz playing with his dolls of Mario, Toadstool, and Bowser. Gaz's mom asks Mario to play with her son, which he agrees to. Mario pretends to be Bowser, and Gaz pretends to be his favorite of the dolls, Geno. Gaz ends up playing too rough however, and activates Geno's "Super Star Shot". Instead of hitting the Bowser doll, the blast accidentally hits Mario, knocking him out.
That night, a single star being enters the Inn. Seeing the four dolls on the floor, the star decides to inhabit the Geno doll. Now possessing the doll, the star has problems with walking, and slams into the wall before leaving the inn. Later, Geno admits he chose that particular doll because it appeared to be the strongest of the four.
The next morning, Gaz tells his mom that he saw the living Geno walk into the Forest Maze. His mom does not believe this, while Mario goes and enters the woods to find the animated doll. Geno enters the forest to challenge Bowyer, and retrieve the Star Piece that Bowyer's minions had found. Mario and Mallow decide to help Geno, and together, the three defeat Bowyer and acquire the Star Piece.
After defeating Bowyer, Geno reveals to the heroes that he is a warrior from Star Road and that he has assumed the form of the Geno doll to fight the Smithy Gang. Additionally, he states that wishes can never come true again until all the Star Pieces are recovered. He also reveals his real name, ♡♪!?. However, this is impossible to pronounce, so the star warrior assumes the name of the doll: Geno. After explaining everything, Geno decides to join forces with Mario and Mallow to find the remaining Star Pieces.
Eventually, Mario, Mallow, Geno, Bowser, and Toadstool collect the remaining Star Pieces and defeat Smithy. With Smithy destroyed, Geno decides to leave the doll's wooden body, returning to the form of a star and bringing the Star Pieces to Star Road. Repairing the celestial road, the power of wishes return to the world. The lifeless Geno doll can be seen sitting behind Mario and company on Vista Hill while they witness Exor disintegrate.