World marathon bronze medallist Kirwa ran aggressively in the women’s race.
She covered the first 5km in 15:45, well inside the pace required to beat the 1:07:26 course record.
Although her pace dropped slightly over the next 5km segment, covering it in 16:06, she stretched her lead over Diane Nukuri from seven to 32 seconds and was still on course-record pace.
“I feel very happy with the win,” said Kirwa. “I also feel very happy because I set a personal best.”
Nukuri finished second in 1:09:23, the second-fastest time of her career and just 11 seconds shy of her PB.
Despite setting a PB of 1:09:29 and running more than a minute quicker than her winning time from last year, Wellings’ performance was only good enough for third place.
Meanwhile the men’s race started relatively slow with the first 5km covered in about 14:27.
The pace then gradually picked up and the 10km mark was reached in 28:50. At that point the lead pack contained 11 runners, including Kifle, Kenya’s Dominic Nyairo, Tanzania’s Fabiano Sulle and Japan’s Keijiro Mogi.
The pace continued to pick up and 15km was passed in about 43:05. By this point the lead pack had been reduced to four runners: Kifle, Sulle, Nyairo and Mogi.
Sulle fell behind over the course of the next few kilometres, and at 20km Kifle led Mogi and Nyairo by four seconds.
Although Mogi and Nyairo tried valiantly to close the gap on Kifle, the Eritrean held on for the win in 1:00:49, one second ahead of Nyairo.
“It was nice to see lots of fans and supporter along the course,” said Kifle after recording the second-fastest time of his career.
Technically speaking, 18-year-old Nyairo was making his half-marathon debut, but the Japan-based Kenyan ran the 23.1km stage at last month’s Hakone Ekiden, passing eight runners en route to clocking 1:07:20 (1:01:30 half marathon pace).