Haw. Rev. Stat. § 702-219

Although ignorance or mistake would otherwise afford a defense to the offense charged, the defense is not available if the defendant would be guilty of another offense had the situation been as the defendant supposed. In such case, however, the ignorance or mistake of the defendant shall reduce the grade and class of the offense of which the defendant may be convicted to those of the offense of which the defendant would be guilty had the situation been as the defendant supposed.