Playing With Your Ninken

Use /pet play when your Ninken's Fun/Care meter has dropped enough to need attention. Playing gives 5–15 Ninken XP and pushes the care timer forward; it does not spend your shinobi's chakra.

Kakashi will refuse the action when the care meter is already at 85% or higher—your companion simply does not need another play session yet. A Ninken that is resting at 10 energy or below also cannot play until its energy recovery finishes.

You can see the current Fun/Care percentage in /pet info. That same panel also handles feeding and washing, so it is the quickest place to check what your companion actually needs before using a care action.