While competing in her native country, the 21-year-old became the 12th winner on the tour this season.
She closed with a 6-under 66, including a rare double eagle at the seventh hole, for a final total of 13-under 203.
The victory was worth $210,000 to Ueda.
"I'm really, really glad I won," she said. "I learned sometimes patience brings fortune."
Ueda entered the final round last year with the lead after shooting 64 Saturday, but shot a 74 in the final round to finish seven shots behind champion Karrie Webb.
Rankin (67) and Hjorth (67) finished 5-under 205 Sunday.
Shinobu Moromizato finished fourth at 8-under 208, while a group of five shared fifth place at 7-under 209.
Laura Davies -- the leader after the first round and a co-leader with Ueda after the second -- was among those who finished six shots back after an even-par 72 Sunday.