Both players played the New Zealand Open six week ago as members of the Japanese contingent in Queenstown and although both missed the cut there, perhaps having some tournament golf under their belt has assisted their cause in this early season event.
22 year old Ohiro has only recently left the amateur ranks while 36 year old Muto has won five titles on the Japan Golf Tour.
The pair is two shots ahead of Daisuke Maruyama, Yuta Ikeda, Nobuhiro Masuda and Joon Woo Choi.
Steve Conran, just one shot further back, leads the Australasians in 7th position, David Smail, Michael Hendry and Adam Bland four from the lead in 11th position.
Scott Strange 22nd and Kurt Barnes 52nd were the only other Australians to make the cut.
Brendan Jones, playing his first event since wrist surgery last September, narrowly missed the cut but was bothered by his wrist pain all week and will now return to Canberra for further consultation on the injury.