The labor union of internet-only Kakao Bank on Wednesday urged management to sweeten its wage deal as its members are set to launch a five-day strike amid little progress in their talks over wage increases and other benefits. The labor union and Kakao Bank's management have been in negotiations over a pay raise and other benefits but failed to narrow outstanding differences. The union said earlier the strike will run from Aug. 31 to Sept. 4. It argued that management should offer better wage proposals in order to avert the planned strike. On July 31, the unionized workers also went on a full strike. In the first quarter of the year, Kakao Bank logged an operating income of 211 billion won ($143 million) on revenue of 1.94 trillion won, both quarterly highs. Unionized workers at the bank's parent, Kakao Corp., and its management, meanwhile, reached a final wage deal earlier this month after a three-month dispute.