Disgaea 4E: A Shared Destiny
The item world is an alternative world that exists inside an item. There are many residents in the item world and most are bad residents called Notorius so you can defeat them. But they can be very strong. Raise your level a good amount before you challenge them or they’ll kill you. By the way, if you want to go into the item world of an equipment you have equipped, you need to take it off. Basically, you’re entering the world of that item so you can’t take it with you. Have extra equipment ready.