In the manga, Ogen tells Oboro that the symbiote creature is Tenzen's twin brother with whom he merged with inside their mother's womb shortly before being born. In the anime however Ogen stops just before telling Oboro where she believed the parasite came from, leaving its identity ambiguous. The anime also expands slightly on Tenzen's backstory, by identifying his mother as an Iga woman who was slain by her lover (a member of the Kouga ninjas and Tenzen's father). Baby Tenzen was then cut from his mother's womb and taken to be raised as a Kouga. Years later the Adult Tenzen would defect to the Iga where, unbeknownst to the others, he secretly manipulated both clans into retaining their hatred for each other in the name of his own vengeance.