Mizuho Financial Group Inc., one of Japan's three mega-banking groups, announced on Tuesday that its net yearly profit fell 4.4 percent to 621 billion yen ($5.2B), citing losses caused by an affiliate consumer lender.

Mizuho sales for the fiscal year rose 15 percent to 4.1 trillion yen ($33.8 billion).

Terunobu Maeda, President of the banking group, said that losses incurred by Orient Corp., a Mizuho partner, played a factor in the profit slide, but declined to give more details.

Consumer lenders such as Orient have faced difficulties after the nation's Supreme Court effectively invalidated so-called '˜gray-zone' rates.

Lenders are now required to pay back borrowers who have been overcharged.

Despite difficulties, the financial group is expecting net profit to increase 20.7 percent to 750 billion yen ($6.3 billion) in the current fiscal year.