Wow, that would have pissed me off.

The same happened to me, except it was Hama. I think i was training, and all of a sudden the enemy casted Hama on the MC.

Yes there are Homunculus in Persona 4.

Also, when you level up your party members S.Links, they can actually protect you in battle. So if a enemy cast mudoon or hama on the MC, then Yukiko or Yosuke can push you out of the way, having the spell hit them instead. THey don't die though, they are left with 1 HP.

I think this happened near the beginning or maybe all the party members died, but i wasn't sure how the Hama passed through.

Oops sorry, i wasn't clear. I don't think there is Homunculus exactly, but there are two accessories that are similar to it.

They are Patient Collar and Partial Award.

Patient Collar can be found in a rare chest at Marukyu Striptease, Void Quest, and Heaven.

Partial Award requires you to ace the second school semester exams.

Sorry for the misunderstanding.