The Labor Newspaper's Legal Consulting Office replied:

Article 460 of the 2015 Civil Code stipulates the responsibility for intentionally giving property not under his/her ownership as follows:

In case the donor intentionally donates property that is not under his/her ownership but the donor does not know or cannot know about it, the donor must pay expenses to increase the value of the property for the awarded when the owner takes back the property.

Thus, if when you receive the donated property without knowing that it is not under the ownership of the donor, the donor must pay costs to increase the value of the property for you when the owner takes property back.