Angle your sword correctly at a cow to untie it without hurting it. This is actually a pretty tough angle to get your sword, so in order to solve this cow puzzle you have to be really smart and careful.
You're trying to untie this cow from the kayak (かい) you're both currently in. Some jerk tied the cow to this kayak and sent it toward a waterfall. If you don't solve this riddle fast, you'll both go with the kayak over the falls!