Japan has started to modify its Civil Code since November 2009, which led to tremendous changes in the warranty system in its sale and purchase agreement. The warranty system was traditionally regarded as a special mandatory liability, however, the draft bill adopted the theory of contractual liability, which required the seller to perform her duty per the contract. The seller will be held liable If the thing given or right transferred is inconsistent with the contract. The buyer’s remedial options include the right to ask for healing the defect, the right to ask for reduction of the price and the right to rescind the contract. If the seller is imputed to the circumstances, the buyer can also claim for damages of performance interest. Regarding whether the seller will be imputed, the draft bill looked into the binding force of the contract, which differed from traditional approach that focused on debtor’s negligence.