The manager of the most expensive Japanese baseball player ever said Thursday that his American purchasers -- who are paying almost $112 million for his services -- had got a bargain. Star Japanese pitcher Yu Darvish, who plays for the Sapporo-based Nippon Ham Fighters, signed a six-year deal to join the Texas Rangers just before a deadline expired Wednesday in the US (Thursday morning in Japan). Darvish, 25, who has an Iranian father and a Japanese mother, has twice been named the Pacific League's Most Valuable Player and fans mourned his departure, while praising his talents and wishing him well in the US major leagues. The Rangers will pay the Fighters a $51.7 million fee for the move, and Darvish himself an annual salary of $10 million, surpassing the sums involved when pitcher Daisuke Matsuzaka signed with the Boston Red Sox in 2006. Even so, Fighters manager Hideki Kuriyama told Japanese media Darvish was underpriced. "He is a pitcher who deserves more," he said in Sapporo. "As a person who has been following the majors closely, I want to say he is better than that." The loss of his star player, he said, would be "tough for our club, but I was prepared to face his departure", according to Kyodo news agency. "I look forward to seeing how he will dominate hitters in the world's most competitive leagues," added Kuriyama, a former professional pitcher who later worked as a Major League Baseball commentator. "I expect Darvish to win at least 18 games (a year)," he said. "He'll get 20 wins if things go really well." Darvish himself shut out the media at a training session in southern Japan, but thanked his fans in a brief message on his blog. He is expected to make a public appearance for the Rangers in the US on Friday, but said he would give a news conference when he returns to Sapporo. "At that time, I want to express my gratitude to people in Japan, including the Fighters fans," he wrote. His supporters said they were sad to see him leave. "Although it's a shame that he is leaving, I will support him as he is sure to be recognised by the world," Shokichi Seno, a 77-year-old member of the Darvish Fan Club in Sapporo, told the Jiji news agency. Yuka Satake, 40, a housewife in Sendai where Darvish went to school, added: "I knew he would definitely go to the major leagues some day. I will go to Texas to cheer him up." Darvish was the highest-paid player in Japanese baseball last year, with earnings estimated at 500 million yen ($6.4 million). He joined the Fighters in 2005 after high school, and has a 93-38 career record and 1.99 lifetime ERA over seven seasons. He went 18-6 in 28 appearances last year, with a 1.44 ERA and 276 strikeouts. Tomoaki Ogura, a 64-year-old popular TV talk show host, echoed Kuriyama's belief that the Rangers' price was "too low". "No kidding. He should be rated much higher," he said.