Jujutsu Kaisen Episode 18 Early Access - Ring Ring

So, while it was hinted at before, I think this ep is when it is directly stated that Megumi is a part of the Zenin clan. As for Kamo talking about Ten Shadow's Technique, that is what Megumi's technique is called, and it is one of the Zenin Clan's hereditary techniques.

"Good doggy. Bad stinky."