Part II
Criminal Responsibility
Right of private defence
12.(1) No act shall be deemed an offence if done in the lawful exercise of the right of private defence.
(2) The right of private defence arises when a person is confronted with the danger of an immediate or imminent assault upon his person, property or honour the person, property, or honour of any other person, and when it is not possible to evade the danger by having recourse to the public authorities, or in any other manner and the said person may combat the danger by what is necessary to combat it and by the appropriate means.
(3) No right of private defence arises against a public servant, acting within the limits of the powers of his post, unless there is apprehension of causing death, or grievous hurt.
(4) The right of private defence shall not extend to willfully causing death, unless the danger to be repelled is apprehended to cause death, grievous hurt, rape, abduction, kidnapping, robbery, armed robbery (hiraba), criminal mischief or damage to public property or establishment or criminal mischief by sinking or by setting fire or by using poisonous, or explosive materials.
Self-defence - national proceedings
EDIT.