After a partial run through of KSM (through the ghost hunters, mist people, and exploding elementals), you are able to reach Mameema, the daughter of storms.
Bring her a seal (from Ys) of the stat you wish to lower and a scroll (from Ys) of the stat you wish to increase (for example a seal of spirit and a scroll of constitution would lower your base spirit by 1 and raise your base con by 1).
You may repeat this a max of 3 times.
Guide (once the area is clear):
ask selous journey
hunt yatha ( n n w s w w w n )
leap 2x
hunt mameema ( u e u e e e n w n )