Mitsuko is Kenji's human grandmother, confirming their direct familial relationship. She practices sorcery, utilizing magical abilities that steal the life force or spirit of men through sexual encounters. This process allows her to maintain a deceptively youthful and stunningly beautiful appearance, masking her true age. The spirit-stealing act results in the death of the men involved, as demonstrated with a security guard and later Dr. Perio. Her lethal encounters, such as the security guard incident where initial resistance gives way to compliance after witnessing her transformed appearance, contain elements of dark humor.

Mitsuko pragmatically assists her grandson Kenji when he rushes to rescue Milfa from Dr. Perio. She ambushes Perio and uses her spirit-stealing ability on him, leading to his death. This action directly resolves the immediate threat Perio posed.