Singer Nezumi Sempai (36) has decided that one year in the limelight is about all he can take. He held a press conference yesterday and told reporters that he plans to retire from showbiz by the end of the year. “Show business is tough, a lot tougher than I imagined,” he said. “And I really haven’t made that much money from it.” With his distinctive punch perm hair and sunglasses that make him look like a typical yakuza, he had a breakthrough last year when his debut single “Roppongi, Giroppon” topped the enka carts and sold over 100,000 copies. But he has failed to follow up on that success and has become the epitome of the “ippatsuya” or one-hit wonder. Before last year’s success he went through about a dozen career changes, including acting in and directing porn movies. But now that he has a young daughter, he said “I won’t be going back to that. From tomorrow, I’m going to go to Hello Work,” referring to the nationwide employment service centers. Before he bows out, he does have one more single on the way. “Okane” (Money) is scheduled for release on June 16 and he will perform a one-night-only concert in Tokyo on June 21.