①Unless otherwise provided for in laws and regulations, any person may freely decide whether or not to conclude a contract.

②Parties to a contract may freely decide the contract terms, subject to the restrictions prescribed by laws and regulations.

①A contract is formed when a party manifests the intention to offer to conclude a contract (referred to as an "offer" below) showing the contract terms and the other party accepts the offer.

②Unless otherwise provided for in laws and regulations, it is not required to satisfy any formalities such as preparation of a written document in order to form a contract.

①An offer which specifies a period for acceptance may not be withdrawn; provided, however, that this does not apply if the offeror reserves the right to withdraw.

②If an offeror does not receive notice of acceptance of the offer referred to in the preceding paragraph within the period referred to in that paragraph, the offer ceases to be effective.

The offeror may deem a delayed acceptance to be a new offer.

①An offer made without specifying a period for acceptance may not be withdrawn until the passage of a reasonable period of time for the offeror to receive a notice of acceptance; provided, however, that this does not apply if the offeror reserves the right to withdraw.

②Notwithstanding the provisions of the preceding paragraph, an offer referred to in that paragraph which has been made to a person with whom the offeror is having a dialogue may be withdrawn at any time while the dialogue continues.

③If an offeror does not receive from a person with whom the offeror is having a dialogue a notice of acceptance of the offer referred to in paragraph (1) while the dialogue continues, the offer ceases to be effective; provided, however, that this does not apply if the offeror manifests the intention to maintain the effect of the offer after the end of the dialogue.

If an offeror dies, comes to be in a constant state wherein the offeror lacks mental capacity, or becomes subject to restrictions on legal capacity to act after issuing notice of the offer, and the offeror has manifested the intention not to make the offer effective should any of these facts occur, or the other party comes to know that any of these facts has occurred before issuing a notice of acceptance, that offer is not effective.

If no notice of acceptance is required due to the offeror's manifestation of intention or customs of the transaction, a contract is formed upon the occurrence of any fact which should be regarded as a manifestation of intention of acceptance.

If the offeree has accepted the offer by adding a condition or making other modifications, it is deemed that the offeree has refused the offer and made a new offer.

A person that makes an offer to the public indicating that a person that performs a certain act will be given a certain reward (referred to as an "offer of reward to the public" below) is obligated to give the reward to the person that performs the act, regardless of whether or not the person performing that act knows of the offer.

①An offeror of reward to the public may not withdraw the offer to the public made by specifying a period during which the requested act should be performed; provided, however, that this does not apply if, in the offer to the public, the offeror reserves the right to withdraw the offer.

②The offer to the public referred to in the preceding paragraph ceases to be effective if no person completes the requested act within that period.

An offeror of reward to the public may withdraw the offer to the public made without specifying a period during which the requested act should be performed, if no person completes the requested act; provided, however, that this does not apply if, in the offer to the public, the offeror manifests the intention not to withdraw the offer.

①Withdrawal of an offer to the public by the same method as the one used to make a previous offer to the public is effective in relation to any person that does not know about it.

②Withdrawal of an offer to the public may be carried out by a method that is different from the one used to make a previous offer to the public; provided, however, that the withdrawal is effective only in relation to persons who know about it.

①If more than one person has performed the act requested in an offer to the public, only the person performing the act first holds the right to receive the reward.

②If two or more persons have performed the act referred to in the preceding paragraph simultaneously, each holds the right to receive an equal share of the reward; provided, however, that the person to receive the reward is selected by lot if the reward is indivisible by nature or if the offer prescribes that only one person will receive the reward.

③The provisions of the preceding two paragraphs do not apply if the offeror manifests an intention to the contrary in the offer to the public.

①If an offer to the public stipulates that only the most outstanding applicant is to receive the reward in the event that two or more persons have performed the act requested in that offer, the offer to the public is effective only if it specifies an application period.

②In the cases referred to in the preceding paragraph, the most outstanding applicant is judged by a person specified in the offer to the public and if no such person is specified in the offer, by the person that makes that offer.

③Applicants may not raise objection to the judge's decision under the preceding paragraph.

④The provisions of paragraph (2) of the preceding Article apply mutatis mutandis if the acts of two or more persons are judged to be of the same level.

A party to a bilateral contract may refuse to perform that party's own obligation until the other party tenders the performance of that other party's obligation (including the performance of an obligation to compensate for damage in lieu of the performance of an obligation); provided, however, that this does not apply if the obligation of the other party is not yet due.

①If the performance of an obligation becomes impossible due to grounds not attributable to either party, the obligee may refuse to perform counter-performance.

②If the performance of an obligation becomes impossible due to grounds attributable to the obligee, the obligee may not refuse to complete counter-performance. In such a case, if the obligor benefits from being released from that obligation, the obligor must reimburse the obligee for the benefit.

①If one of the parties promises in a contract to render a certain performance to a third party, the third party has the right to claim that performance directly from the obligor.

②The validity of the contract referred to in the preceding paragraph is not impaired even if a third party does not exist or a third party is not specified at the time of its formation.

③In the case referred to in paragraph (1), rights of the third party accrue when the third party has manifested intention of availing of the benefit of the contract under that paragraph to the obligor.

①After rights of the third party have accrued pursuant to the provisions of the preceding Article, the parties may not modify or extinguish those rights.

②If, after rights of the third party accrue pursuant to the provisions of the preceding Article, the obligor does not perform the obligation to the third party, the other party to the contract referred to in paragraph (1) of that Article may not cancel the contract without the consent of the third party.

The obligor may duly assert a defense based on the contract referred to in Article 537, paragraph (1) against a third party that benefits from the contract.