If Jyushimatsu ever got possessed, it would have to be by a very strong, malicious spirit. Jyushimatsu’s resilience is very strong, after all.
Jyushimatsu, being of strong mind and body, would force himself into a lockdown as he battled for control with the spirit. It’d all be mental so no one else can actually tell what’s going on www
The stronger the spirit, the longer it takes for Jyushimatsu to overcome it. In the meantime, his brothers try to help him out the best they can (watching over him, making sure he doesn’t move, restraining him if necessary, etc.)
The vending machine incident involved soul-sucking and Jyushi being thrown into hyperspace but that’s another story.
Since Jyushimatsu is the most knowledgeable about fending off spirits, his brothers can’t really do much except try textbook procedures. Their added help in addition to Jyushimatsu’s natural resilience often get rid of all spirits.
