He was portrayed by Warner Oland.
Dr. Yogami was a werewolf who had been searching for a plant known as mariphasa in Tibet, which would cure him of his lycanthropy. One night, he transformed while he was searching for the plant,
and he attacked and bit another scientist, Dr. Glendon, who had taken three of the plants for research. He managed to track Glendon down in London and told him he had met him one night in Tibet. Glendon is confused as he doesn't realize he was the creature that attacked him. Yogami convinces Glendon that he had become a werewolf and that the plant he had taken is the only thing that can cure him, besides death. He also convinces him that a werewolf seeks to kill the one he loves most. This is all in his plan for Glendon to bloom them so that he can steal them for himself to prevent him from transforming during the full moon. The night Glendon is about to transform, Yogami sneaks into his lab and steals the only two blossoms (as the third one hasn't bloomed yet), disregarding the fact that Glendon will go on a murder rampage as a result of what he did.
After a time, the third blossom of the mariphasa finally blooms, but much to Glendon's horror, it is stolen by Yogami, sneaking into the lab while Glendon's back is turned. Catching Yogami in the act, Glendon finally realizes that Yogami was the werewolf that attacked him in Tibet. Glendon tries to stop him, but Yogami has already used it on himself. The two begin to fight until Glendon transforms and kills Yogami.