MOSCOW—A Japanese space tourist said Wednesday that he felt his 12-day mission to the International Space Station was too short and he would love to stay a week more. Fashion tycoon Yusaku Maezawa, his producer Yozo Hirano, and Russian cosmonaut Alexander Misurkin blasted off to the station in a Russian Soyuz spacecraft on Dec. 8 and returned to Earth on Monday. “It takes three or four days to adapt and then you realize that there are just eight days left and it’s not enough,” Maezawa told reporters via a video link from the Star City space flight training facility where they undergo post-flight checks. “A 20-day mission would be ideal, but 30 days would be too much for me,” he added. Maezawa, 46, and his 36-year-old producer Hirano were the first self-paying tourists to visit the space station since 2009. Misurkin was on his third space mission. Asked about his …