All you need is:

1)shotgun (Azure)
2)pellet s lv2 (max)
3)clust s lv3 (max)
4)pellet s lv1 (max, just in case)

start the quest and collect the items you need from the box use the 2 rations and head to area 7 (best route is 1, 3, 7). when your there if the yian kut-ku isn't there use the pellet s lv 1 to slay the velocipray. then when the yian kut-ku arrive go to the ledge but dont climb it draw the yian kut-ku there when its there climb up and stand back. switch to your pellet s lv2 and fire all 60 shots at the yian kut-ku. when your out of pellet s lv2 switch to the clust s lv1 and two shots should kill it