Peach agrees in exchange, TEC lets her send e-mails to Mario. Peach then meets TEC-XX, who develops an interest in Peach's concept of love, and asks for her help to understand it. Grodus hears this and orders the Shadow Sirens to steal the map in Mario's possession. When a X-Naut tells Sir Grodus someone got the first Crystal Star, Peach accidentally blurts out Mario's name.
Somewhere else, it is revealed that Princess Peach was abducted by the X-Nauts. After navigating through the castle's traps with the help of Koops, they encounter the dragon and defeat her, allowing Koops's father to get out of the dragon's gut and present Mario with the Diamond Star. After finding them, Mario and Goombella march to Hooktail's castle, with Koops in tow (who wants to defeat Hooktail to avenge his dead father and become stronger). The mayor tells them that Hooktail guards the Crystal Star in her castle, and that to access it, they must find the two stone keys in Shhwonk Fortress. The duo stops at a nearby village called Petalburg and discover from the mayor that the dragon Hooktail has been terrorizing the village. After finding it, Mario and Goombella arrive in Petal Meadows, where they see Hooktail and her castle. To reach this place, they must find a pipe in Rogueport Sewers. Mario and Goombella show the updated map to Professor Frankly, who reveals that the first Crystal Star is in Petal Meadows. So, Mario holds the map before the Thousand-Year Door, revealing the location of the first Crystal Star. Said objects can be found by holding the Magical Map before the Thousand-Year Door, which is located in the town's sewers. At the professor's house, Frankly explains that the map is related to the legend of the treasure of the Thousand-Year Door, and that, to obtain the treasure, one must first open the door with the seven Crystal Stars. Then, Goombella suggests to go to Professor Frankly's house, to consult him and show him the map. As Goombella is also searching for the map's treasure, she decides to join Mario. After defeating the X-Naut general and escaping from the X-Nauts, Goombella introduces herself, and Mario explains his quest to her. Mario intervenes and Lord Crump tries to defeat him.
Shortly after Mario reaches Rogueport, he finds Lord Crump attempting to interrogate Goombella about the Crystal Stars. Mario receives the letter with the map and decides to help her, and thus boards a ship to Rogueport. Soon after that, she is kidnapped by Sir Grodus. She sends this to Mario, along with a letter asking him to help her search for the map's treasure. The adventure begins when Princess Peach goes on a cruise to Rogueport where she meets a hooded woman, and buys a box which contains a map. Mario and Goombella about to be jumped by the X-Nauts.