Hanarin is the owner of the Halmi mask (the old widow). She is an adult chachaoong and it is said that she is almost as old as Jack. As such, she has probably been around far longer than almost everyone else. Though the exact reason is not stated, she has the somewhat questionable tendency to stalk young girls and is currently following Ara around. As such, she is freeloading at Yu Jin's house along with most of the other Tals since Ara has taken up residence there.
It has been stated that Hanarin changes her appearance (possibly to look younger) so it is unknown what her real appearance is. However, when using her ability, she looks like an attractive woman, possibly in her 30s. Like many of the older chachaoongs, Hanarin prefers more traditional style clothing and is usually seen a sort of sleeveless hanbok, with a shawl or wrap. Her dark hair is kept back with an ornate hairpiece and she has blue eyes.
She is very beautiful and seems fairly young but is referred to as a "granny" or "hag" by many of the other Tals. She is slightly taller than Jin and was initially disturbed that a boy shorter than her was the new king, much less Ara's chosen object of affection.
Hanarin is mostly apathetic in regards to anything except what relates to Ara, where she becomes protective and often jealous. She even goes out of her way to do things she woud rather not do, just for Ara's sake. She seems to have very little drive to do anything except stalk and obsess over Ara.
It is unclear if her obsession with the girl is romantic or otherwise, but most of the other Tals living with Jin seem to find it on the creepy side, though Ara seems fairly oblivious to the whole thing.
Somewhat lazy, Hanarin is also quick to complain when she does have to use her abilities or work, and generally exhibits a somewhat crotchety personality befitting of someone of her age.
Hanarin has the ability to read fortunes and see hidden details about a person's past and future. She appears to use uncooked rice as a means to read these fortunes (much like reading tea leaves or palm reading); however, this ability will not work on everyone as she was unable to read Jin's fortune at all. She also cannot see all the details of even a person whose fortune she would normally be able to read, as she was unable to see where Imae had vanished to for two years, much to his relief.
Hanarin also has something referred to as "the chasing ability". She can use this ability for real-time tracking of other people (something like a GPS as Jin and Maru noted). This ability puts a great deal of strain on her and can leave her ill for days, but allows her to track even moving targets. For this ability, Hanarin summons her yongma, which is a gold, glowing being that has a spiritual body and no conscious mind. Rather, she uses it like a tool for the purposes of finding someone's location.
It is also noted that she can sense Ara's presence within a 5km radius 'without fail', though it is unknown if this is specific to Ara or if it applies to anyone that she is focused on; but it does not seem to involve the same physical strain as her chasing ability and is most likely unrelated.
Presumably, she has combat-based abilities as well, as Imae is relieved that he does not have to fight her, but these are yet to be demonstrated if they exist.
Ara - Ara is the only person with whom Hanarin seems to have a significant relationship. It is unclear exactly what her motives for following Ara are, but it is implied by the others that it is for less than savory reasons. Although Ara seems to view Hanarin as more of a mother-type figure (if that), Hanarin displays extreme devotion and affection for the girl, getting quite jealous when others speak to or touch her.
Aside from the fact that she is one of the oldest chachaoongs aside from Jack himself, little is known about her past prior to coming to stay with Jin. It is revealed that she has a habit of stalking young girls and is sensitive about her age, going so far as to change her appearance, presumably, to look younger.
She first appears in the story after following Ara to Jin's house. In general, she does not seem to be well-liked by the others, but this could be due to her complaining, apathetic attitude more than past negative experiences. She seems to mostly be waiting for Ara to lose interest in Jin, but this does not seem likely to happen any time soon.