After a scoreless regulation and first overtime period, the Eagles (10-7-4) struck quickly in the second extra frame. Senior Courtney Collins sent a cross in from the right wing that found Hirano in stride at the top of the 6-yard box. The rookie from Watkinsville, Ga., nodded it home into the lower left corner for the clinching goal, her third of the season.
The contest was GSU's second straight in the tournament decided by a freshman in the waning minutes. In last Sunday's first-round upset of top-seeded UNCG, freshman Nora El-Shami had the game-winner in the 89th minute.
Georgia Southern keeper Katie Merson finished with three saves for her SoCon-best ninth shutout of the season and third in a row.
The Eagles will be making their first title match appearance since 1996 and will be seeking their first title.
Georgia Southern was the more aggressive team throughout, outshooting Elon 15-5 for the contest. The Eagles had a 3-1 shot advantage in the first extra period and notched the lone attempt of the second one.
Georgia Southern's Alex Murphy nearly ended the contest in the first overtime, sending a curling shot toward the upper left corner of the goal from inside the 18-yard box in the 97th minute. Elon keeper Kate Murphy made a nice stop to keep the game going, using every bit of her 5-9 frame to snag it and keep the game scoreless.
Moments earlier, Elon's Nicole Dennion fired a shot wide from about 20 yards out.
The Eagles had the statistical edge in the first half, outshooting Elon 5-2. GSU took the first three shots of the day, with Kate Murphy making a pair of saves.
Despite having just a pair of shots in the opening stanza, it was Elon that applied more constant pressure in Georgia Southern's defensive third, but only Taylor Glenn's shot was on frame.
Georgia Southern came out the more aggressive team after halftime, with Stephanie Gratto and Alex Murphy ripping shots in the first seven minutes that forced saves from Kate Murphy.
Kate Murphy came up with another nice save on Gratto's long-range shot in the 58th minute as the Eagles continued to dictate the pace of play in the early going.
The Phoenix (7-9-6) had a solid scoring chance in the 67th minute, but Mel Insley's free kick from 40 yards out was just out of the reach of a sliding Shannon Foley inside the 6-yard box.
Elon cranked up the offensive intensity after that. Glenn put a ball in the back of the net in the 77th minute, but the goal was disallowed when a foul was called on the Phoenix at the top of the 18-yard box.
Minutes later, Simi Dhaliwal put a well-struck shot on frame, but Merson was there for the save.
El-Shami, who had the 89th-minute game-winner against top-seeded UNCG in the first round, nearly struck again late in Friday's match, but her shot on an Eagle set piece rattled off the right post and out of harm's way in the 80th minute.
Kate Murphy took the tough loss, making eight saves on the night.
2012 SoCon Women's Soccer Championship
Semifinals, Friday, Nov. 2
Semifinal 1: No. 8 seed Georgia Southern 1, No. 5 seed Elon 0, 2OT
Semifinal 2: No. 7 seed College of Charleston vs. No. 3 seed Furman, 7:30 p.m. CT (SoCon.TV)
Championship, Sunday, Nov. 4
Winner of Semifinal 1 vs. winner of Semifinal 2, 1 p.m. CT (ESPN3)