"You may have already seen him but there is a Hunter named Ken at the south of the Salt Mines. This guy made a really difficult request. Would you like to hear it? Ken's note should be here somewhere... Ah, here it is. Let's see. "...Send me someone that has passed these five tests. I have a request to make." He says the first test is to hunt the Gallus that live in front of the East Gate of Horizon. What do you say? Are you interested in taking the challenge?"
After accepting the quest, head east out of Horizon. Gallus can be found in the field just east of Horizon that stretches east and then turns south. Kill the required number of Gallus and then return to Guild Official Oveli.
"Good work. There are still four tests left. Will you continue?"