Even though the contract is not constituted, one of the parties is responsible for the injury caused to the other party who without his own negligence believed in the constitution of the contract when he, in order to prepare or negotiate for the contract, has done either of the following:
(1) Hidden in bad faith or dishonestly explained the gravely relevant matter of the contract when the other party inquired.
(2) Intentionally or gross negligently spilt out the other party's secret known or held by himself which the other party has explicitly expressed to be kept in secret.
(3) Any other matter obviously against good faith.
The claim for the injury in the preceding paragraph shall be extinguished by prescription if not exercised within two years.

If the prestation of a contract is impossible, it is void. However, if the impossibility can be removed and if the parties, at the time when the contract was constituted, intended to have it performed after the removal of the impossibility, the contract is still valid.
If the contract is subject to a suspenseful condition or to a time of commencement, and if the impossibility has been removed prior to the fulfillment of the condition or the arrival of the time, the contract is valid.

When a contract is void on account of the impossibility of the performance, the party who at the time of constituting the contract knew or might know the impossibility is responsible for the injury caused to the other party who, without his own negligence, believed in the validity of the contract.
The provision of the preceding paragraph shall be mutatis mutandis applied if the prestation is partially impossible and the contract is valid in respect to the possible part, or if one of the several prestations subject to a choice is impossible.
The claims for the injury in the preceding two paragraphs shall be extinguished by prescription if not exercised within two years.

If a contract has been constituted according to the provisions which were prepared by one of the parties for contracts of the same kind, the agreements which include the following agreements and are obviously unfair under that circumstance are void.
(1) To release or to reduce the responsibility of the party who prepared the entries of the contract.
(2) To increase the responsibility of the other party.
(3) To make the other party waive his right or to restrict the exercise of his right.
(4) Other matters gravely disadvantageous to the other party.

When one of the parties to a contract receives earnest money from the other, the contract is presumed to be constituted.

Unless otherwise agreed upon by the parties, the following rules apply to the earnest money:
(1) When the contract has been performed, the earnest money shall be returned or treated as one part of the payment.
(2) If the contract cannot be performed owing to a circumstance to which the party who gave the earnest money is imputed, such party shall not claim for the return of the earnest money.
(3) If the contract cannot be performed owing to a circumstance to which the party who received the earnest money is imputed, such party shall return double amounts of earnest money.
(4) If the contract cannot be performed owing to a circumstance to which neither of the parties is imputed, the earnest money shall be returned.

The parties may agree on a penalty to be paid by the debtor in case the debtor does not perform the obligation.
Unless otherwise agreed upon by the parties, the penalty shall be deemed to be the total amount of damages due to the non-performance. If it is agreed that the penalty shall be paid when the debtor does not perform the obligation at the agreed time or in the agreed way, this penalty shall be deemed to be the total amount of damages due to this non-performance, besides the creditor may claim for the performance.

If the obligation has been partially performed, the court may reduce the penalty proportionately as the interests received by the creditor due to the partial performance.

If the agreed penalty is disproportionately high, the court may reduce it to a reasonable amount.

The provisions of the preceding three articles shall apply mutatis mutandis to the agreed non-pecuniary payment for the breach of a contract.

When a party to a contract is in default, the other party may fix a reasonable period and notify him to perform within that period. If the party in default does not perform within that period, the other party may rescind the contract.

If according to the nature of the contract or the expression of intent of the parties, the purpose of the contract can not be accomplished if not performed within the fixed period, and if one of the parties does not perform the contract within that period, the other party may rescind the contract without giving the notice specified in the preceding article.

In cases provided by Article 226, the creditor may rescind the contract.

If there is no deadline for the exercise of the right of rescission, the other party may fix a reasonable one and notify the party having the right of rescission to make a definite reply within such deadline whether he will rescind the contract or not. If the notice of rescission is not received before such deadline, the right of rescission is extinguished.

The right of rescission shall be exercised with the expression of intent to the other party.
If there are several persons on either side of the contract, the expression of intent specified in the preceding paragraph shall be made by all of them or to all of them.
The expression of intent to rescind a contract shall not be revoked.

Unless otherwise provided by the act or by the contract, each party shall, in case of rescission, restore the other party to his status quo ante according to the following rules:
(1) Each party shall return the prestation received to the other party.
(2) If the prestation received consisted of money, interest calculated from the time of receipt shall be added.
(3) If the prestation received consisted of service or of the use of a thing, the value of such service or use at the time of receipt shall be reimbursed in money.
(4) If a thing to be returned has produced profits, such profits shall be returned.
(5) If necessary or beneficial expenses of the thing to be returned have been paid, such expenses may be claimed for to the extent to which the other party is benefited at the time of return.
(6) If a thing to be returned has been damaged or destroyed or cannot be retuned owing to any other cause, its value shall be reimbursed.

The exercise of the right of rescission does not prejudice to the claim for compensation.

The provisions of Articles 264 to 267 shall mutatis mutandis apply to the mutual obligations of the parties resulting from the rescission of the contract.

When the person entitled to the right of rescission is imputed to the damage or destruction of the thing received or any other circumstance which causes the return impossible, his right of rescission is extinguished. The same rule shall be applied when the kind of the thing received has been altered by process or remodeling.

The provisions of Articles 258 and 260 shall be mutatis mutandis applied when the parties terminate the contract in accordance with the provisions of the act.

A party to a mutual contract may refuse to perform his part until the counter-prestation has been performed by the other party, except he is bound to perform first.
When one party has partially performed his part, the other party shall not refuse his counter-prestation if circumstances are such that a refusal to perform would be against the manners of good faith.

A person who is bound to perform his part first may, if after the constitution of the contract the property of the other party have obviously decreased whereby the counter-prestation might become difficult to be performed, refuse to perform his part, until the other party has performed his part or furnished security for such performance.

If none of the parties is imputed to the impossibility of one party's performance, the other party shall be released from his obligation to perform the counter-prestation. If the impossibility is only partial, the counter-prestation shall be reduced proportionately.
In the case provided in the preceding paragraph, if the counter-prestation has been wholly or partially performed, it may be claimed for the reimbursement in accordance with the provisions concerning Unjust Enrichment.

If one of the parties is imputed to the impossibility of the other party's performance, the later may claim for the counter-prestation, but the interests saved or ought to be saved arising from the release of the performance shall be deducted from the counter-prestation claimed.

One of the parties to a contract who has undertaken that an obligation shall be performed by a third party shall be responsible for the injury if the third party does not perform the obligation.

When it is provided in a contract that an obligation shall be performed to a third party, the offeror may demand the debtor to perform the obligation to the third party, and such third party also has the right to demand performance direct from the debtor.
So long as the third party has not expressed his intent to take advantage of the contract specified in the preceding paragraph, the parties may modify the contract or revoke it.
If the third party expresses to either of the parties his intent not to take advantage of the contract, he is deemed to never have any right under the contract.

The debtor specified in the preceding article may take all the valid defenses arising out of the contract against the beneficial third party.