It is basically possible to make a special agreement to disclaim the seller’s obligation regarding defects. However, the seller may not be released from the responsibility if the seller knew but did not disclose the defects to the buyer even if the seller makes a special agreement.*Civil Code(Special Agreement Disclaiming Warranty)Article 572: Even if the seller makes a special agreement to the effect that the seller does not warrant in the case prescribed in the main clause of Article 562, paragraph (1) or Article 565, the seller may not be released from that responsibility with respect to any fact that the seller knew but did not disclose, and with respect to any right that the seller personally created for or assigned to a third party.