JAPAN'S oldest bank has ventured into banking in Hongkong to cater for a growing volume of Japanese investment in the territory and because of the promising banking market. ''Recently, many of our clients in Japan have invested in Hongkong. Therefore we've come here to assist them,'' said Daishi Bank president Jisuke Suzuki at yesterday's branch opening ceremony. The bank, with a full Hongkong banking licence, now limits its services to wholesale and private banking but may expand into the retail sector. ''I think Hongkong as a financial centre in Southeast Asia is of vital importance to us,'' Mr Suzuki said. ''As Hongkong's economy has been strong so far, it offers much more opportunities for business compared with other markets. ''We hope there will be many chances for us to get regional clients from here.'' This is the bank's second overseas branch - the other is in New York - but Mr Suzuki believed the Hongkong branch would be the busier of the two. Before the branch was opened, the bank served clients through a representative office. ''Operation of the representative office was quite restricted . . . Now we can provide much more service to our clients,'' Mr Suzuki said. The branch initially will cater primarily for existing Japanese clients but eventually will expand from this base.