Japanese businessman Daisuke Enomoto, who paid and trained for a 10-day flight aboard the International Space Station, is suing to get back his $21 million dollars, after being pulled from the three-member crew for medical reasons a month before liftoff. In the lawsuit, posted on the Internet by Wired magazine, the 37-year-old Enomoto says the medical condition cited for his removal from the crew -- kidney stones -- was well known by the doctors who monitored his health and suitability for space flight. Dallas businesswoman Anousheh Ansari, founder of Texas-based consumer technology company Prodea Systems, caught the September 2006 flight instead Enomoto filed suit last month in the U.S. District Court against Virginia-based Space Adventures, the space tourism company that plans to send its sixth paying passenger to orbit next month. Enomoto alleges he was pulled from the flight so Ansari, who had invested in Space Adventures, could fly instead. In a response filed on Wednesday, Space Adventures' lawyers said Enomoto's contract did not entitle him to a refund if he became medically disqualified. Enomoto made international news when it was revealed that he intended to go into space wearing a costume of a character from the anime series Gundam.