Under California law, criminal homicide is divided into two major classes: the greater offense of murder and the lesser included offense of manslaughter. (People v. Rios (2000) 23 Cal.4th 450, 460.) "Murder is the unlawful killing of a human being . . . with malice aforethought." ( 187, subd. (a).) Malice may be express or implied. ( 188.) "'A killing with express malice formed willfully, deliberately, and with premeditation constitutes first degree murder.' . 'Second degree murder is the unlawful killing of a human being with malice aforethought but without the additional elements, such as willfulness, premeditation, and deliberation, that would support a conviction of first degree murder.' . Thus, the mens rea required for murder is malice, express or implied." (Elmore, supra, 59 Cal.4th at p. 133.) Manslaughter, by contrast to murder, is the "unlawful killing of a human being without malice." ( 192.) Manslaughter is divided into three categories: voluntary, involuntary, and vehicular. (Ibid.) A killing perpetrated in imperfect, or unreasonable, self-defense lacks malice and gives rise to criminal liability for voluntary manslaughter. (In re Christian S. (1994) 7 Cal.4th 768, 783.) "'One who holds an honest but unreasonable belief in the necessity to defend against imminent peril to life or great bodily injury does not harbor malice and commits no greater offense than manslaughter.' ." (Elmore, supra, 59 Cal.4th at p. 134.) Imperfect self-defense is "'not a true defense; rather, it is a shorthand description of one form of voluntary manslaughter.' ." (Ibid.) Imperfect self-defense "involves a misperception of objective circumstances, not a reaction produced by mental disturbance alone." (Elmore, supra, 59 Cal.4th at p. 134.) Accordingly, imperfect self-defense supporting a voluntary manslaughter conviction cannot be based on delusion alone. (Id. at p. 146; Mejia-Lenares, supra, 135 Cal.App.4th at p. 1461.) Rather, a claim of imperfect self-defense where the defendant's honest but irrational perception of imminent harm or death is distorted by his mental illness must be based on a misperception of objective circumstances that actually exist at the time of the killing. (Elmore, supra, 59 Cal.4th at p. 146 "Defendants who mistakenly believed that actual circumstances required their defensive act may argue they are guilty only of voluntary manslaughter, even if their reaction was distorted by mental illness.".) A defendant who claims he killed in self-defense because of a purely delusional belief that he faced an imminent threat of death of great bodily harm must raise that claim at a sanity trial. (Ibid.) "Unreasonable self-defense and legal insanity are distinct theories, and must be adjudicated separately." (Ibid.) Voluntary manslaughter arising out of a killing perpetrated in imperfect self-defense is a lesser offense included in the crime of murder. (People v. Barton (1995) 12 Cal.4th 186, 201-202 (Barton).) A trial court must instruct on all lesser included offenses supported by substantial evidence. (People v. Duff (2014) 58 Cal.4th 527, 561.) "Whenever there is substantial evidence that the defendant killed in unreasonable self-defense, the trial court must instruct on this theory of manslaughter." (Elmore, supra, 59 Cal.4th at p. 134.) The trial court has no duty to instruct on imperfect self-defense when the evidence suggesting the defendant killed in imperfect self-defense is "minimal or insubstantial." (Barton, supra, 12 Cal.4th at p. 201.) Substantial evidence is evidence "sufficient to 'deserve consideration by the jury,' that is, evidence that a reasonable jury could find persuasive." (Id. at p. 201, fn. 8.)