Supernatural: The Anime Series (2011)

S01E08 Everlasting Love

Sam and Dean delve into a string of serial killings that have mysteriously recurred every 15 years since the 1960s. Their investigation leads them to Dr. Richard, a grieving widower, and his stunningly young second spouse, Michelle. As they dig deeper, more brutal incidents unfold, heightening the urgency of their quest to unravel the dark history behind these chilling events.