In a recent series on credit information reporting, the Asahi Shimbun explained the plight of a young Kanto woman who had applied for a credit card last March. The card she was interested in offered discounts at selected stores and could be used as an IC card for public transportation. It also had an attractive point system. Almost all her work colleagues had the card and since her financial particulars were the same as theirs she didn't think she'd be turned down, but she was and the rejection confused her. She had one other credit card, which she had always paid on time. When she called the credit company that refused her they said they couldn't give her the reason for the rejection.
Then she received a letter from Softbank Mobile, her cell phone service carrier, which said that due to a mistake her payments had been reported to a credit information (CI) company as being delinquent. The period of her false delinquency, she realized, fell during the same time that she applied for the credit card. In the letter Softbank said that it had corrected the mistake with the CI company, and when she applied for the card again after a while, she was approved, but when she tried to find out why they had changed their mind the company again said they couldn't tell her.
Such situations are not uncommon, but since credit card companies are not obliged to give reasons for rejecting or accepting customers, most applicants have no idea that these problems even exist until it's too late.