<P> The Thousand - Year Door contains several characters, the majority of whom are not playable . Progression in the game is sometimes dependent on interaction with non-player characters, although many are used in the game's various subquests . In particular, the Goomba Professor Frankly, who knows the most about the mysteries relating to Rogueport, must be visited every time Mario retrieves a Crystal Star . The game continues the tradition of Paper Mario, in which Mario can be accompanied by one assistant character at a set time . There are seven party members in total: Goombella the Goomba, Koops the Koopa, Madame Flurrie the wind spirit, a Yoshi (named by the player), Vivian the Shadow Siren, Admiral Bobbery the Bob - omb, and Ms. Mowz, who is available as an optional character . </P> <P> Mario is the main character of The Thousand - Year Door, although the story also rotates between portions where you play briefly as Princess Peach and Bowser . Most of Peach's story is spent on her interaction with the X-Naut's computer AI TEC, who falls in love with Princess Peach despite not fully understanding the concept of love . Princess Peach agrees to teach TEC about love in exchange for the ability to contact Mario via e-mail . The main antagonist of the Mario series, Bowser, tries to collect the Crystal Stars before Mario does instead of directly opposing Mario, though his attempts mostly become comedic relief . Luigi's role in the game is that of an NPC and consists of recounting his slapstick adventures in the Waffle Kingdom, appearing in Rogueport with party members of his own, many of whom do not like Luigi at all for various reasons, juxtaposing the universal respect Mario's partners have for Mario . Ironically, Luigi winds up having his adventures actually printed and published . The books becoming best selling novels that are eventually purchasable through the in - game item shops, though the stories told in the novels greatly exaggerate Luigi's heroics, compared to stories directly told Luigi's disgruntled partners or even Luigi himself . </P> <P> The game opens with an introduction about a seaside town which was damaged by a cataclysm and consequently sunk into the depths of the earth . A town named Rogueport was later built at this site, with the fortunes of the lost kingdom fabled to exist behind the eponymous Thousand - Year Door, located in the ruins of the old town . Mario becomes involved when Princess Peach contacts him about a treasure map that she bought in Rogueport, but becomes part of a larger adventure after learning that Peach has gone missing . With the help of Goombella and Professor Frankly, Mario learns that the map can potentially reveal the location of the seven legendary Crystal Stars, which are required to unlock the Thousand - Year Door . Under the assumption that Peach herself is trying to find the Crystal Stars, he uses the map in an attempt to locate her . </P> <P> In actuality, Peach has been kidnapped by the Secret Society of X-Nauts, a group led by Sir Grodus that are also searching for the Crystal Stars . While held captive, Peach uses e-mail via the main base's computer, TEC, to inform Mario about the quest and consequently help him to attain all seven Crystal Stars and locate the treasure . However, the "treasure" is actually the Shadow Queen, a demon responsible for the ancient cataclysm that destroyed the original town 1,000 years ago . The X-Nauts had kept Peach so that her body could be possessed by the Shadow Queen in a bid to recover her full power . This happens, but the arcane power of the Crystal Stars is then used to separate Peach from her possessor briefly to give Mario and friends the strength needed to fight the Shadow Queen . The game ends when Mario defeats the Shadow Queen and frees Peach, returning home with her . </P>

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