Snipe first, Mei in ambush

There was a large number of them, and the couple thought that thinning their number first and then finishing the rest off would be the best way to go about this.
Mei would be hidden and wait for her chance to join the battle and ambush the demons once they were sieging Ren...

It sounded like a good plan, and they acted on it.

Ren activated his Human Eye and began to snipe them from as far as he could possibly be while keeping as many of them in sight.
The sneack attack worked like a charm and a dozen of them died before they even noticed where the arrows where coming from... more got offed on their way, and by the time the Jakis reached them only 5 of them were left.

The only reason they didn't immediately flee was because they felt that Ren looked like a weakling and the only reason he was able to kill so many was thanks to his bow, so now that they got closer he would have no way to fight back and they could avenge their comrades... an empty hope.

Mei didn't even need to come out herself as Ren was able to handle all five of them on his own, and soon the couple could harvest the 18 coins worth of demonic cores.
This turned out to be not only an easy fight, but also a very profitable one!