In Monster Apartment, the hilarious and heartwarming stories of the protagonists continue. At the end of the previous season, Mr. P had intended to evict all the tenants but was ultimately defeated by a sudden bout of the flu. Under the careful care of Diudiu and the others, Mr. P decided to let everyone stay. The elusive Dr. Qi, mistaken by Diudiu as a midnight ghost, turned out to be just a very reclusive scientist. Monster Apartment welcomes new tenants: Young Master Boban and his butler, Bozai. They bring a "trash artifact" that leaves all the tenants in awe. At the end of the story, Diudiu receives a job offer from another planet, and farewells are imminent...