Ricardo Medina Jr. -- one of the stars of 'Power Rangers Samurai' -- was just sentenced to 6 years in prison for stabbing his roommate to death with a sword.
Ricardo appeared in court Thursday where the judge handed down the maximum sentence, 2 weeks after the actor pled guilty to voluntary manslaughter, and admitted he used a sword in the killing.
TMZ broke the story ... Ricardo was rearrested back in January 2016 and charged with murder. He had previously been arrested, but the D.A. kicked the case back to cops for more investigation.