Question

greg is a regular boy who tries to do his best in school but who also happens to have a magical unicorn. when hes not studying and playing baseball on earth, greg is riding his unicorn through the enchanted land of harmonia. when greg brings something to harmonia that he shouldnt, a secret gate is unlocked and the muck - muck monsters are unleashed, causing terrible pollution in harmonia. can greg and his unicorn stop the monsters before they reach earth?
character vs. character
character vs. society
character vs. technology
character vs. supernatural

Explanation:

Greg (a character) has to stop muck - muck monsters (supernatural entities). The conflict is between a character and supernatural elements.

Answer:

Character vs. Supernatural