The victory comes nearly seven years after Teshima's last victory at the Casio World Open in 2007.
Scott Strange finished the week as the leading Australian in a share of 14th position with Michael Hendry 25th and Steve Conran 28th.
Hendry, in 13th position, is the best of the Australasians on the Japan Tour money list.
The Japan Tour has a one week break during the US Open and returns the following week at their Tour Championship in Ibaraki.
Want video tips delivered straight to your inbox? Subscribe to iseekgolf.com newsletters.