Tomie Kawakami is the main character in the manga series of the same name. She has the ability to regenerate herself into multiple clones, which is a recurring theme in stories featuring Tomie.
Tomie Kawakami is a young woman frequently described as almost impossibly beautiful by those she meets. The specifics of her appearance vary depending on the story, but she always has long (often straight) dark hair and a small mole underneath her left eye.
Tomie is a manipulative, hedonistic, and extremely selfish woman, seducing men to do her bidding. She is one of Junji Ito's most recurring characters, appearing for a grand total of 3 series: Tomie, Tomie: Part 2 and Tomie Again.
There have been numerous live-action adaptations of Tomie's stories, with the character herself portrayed by a wide variety of actresses.
Source of Obsession
Tomie's mere presence seems to drive people to become fixated on her, either positively or negatively. People thus enthralled tend to feel a mixture of intense love and hatred towards her, often beginning as the former and shifting towards the latter over time.
Tomie is able to regenerate herself from the smallest living piece of herself, including hairs, skin, and drops of blood. Each separate piece can grow into a full clone of herself, with its own independent mind. The only way to prevent Tomie's regeneration is to burn every part of her, leaving nothing for her to grow from.
Tomie's regeneration takes time but can be expedited by bringing her food or striking her with concentrated radiation. "Little Finger" implies that she can either control her regeneration if she wishes or that her regeneration works faster if she can manipulate someone into bonding with her.