Rin Asogi's story began over 1,000 years ago, when she was a traveler who had gotten herself killed by bandits in Japan. Problem was – she came back to life. The first person to see her was Tajimamori, who at the time was the guardian of the life tree Yggdrasil. Enraptured – and at the same time bewildered on why she died and came back to life, Rin pleaded with Tajimamori for answers, but he drew back, knowing the nature of what had happened to her. Sometime in her life, Rin became infected by what was called a Time Fruit, which made her immortal.
Since becoming an immortal, Rin has struggled to put meaning to her extended life by becoming a champion of justice, be it standing-up for others – or by fighting off the sadistic immortal Apos, who plans to use her to become a permanent guardian of Yggdrasil rather than passing it on to Rin's future child. In the latter years of the 20th Century, she established a firm, Asogi Consulting, along with Mimi, another immortal she rescued from an angel years before, as well as Genta, their immortal dog. She also has a working relationship with Tokyo police detective Yanagihara, although later on it is hinted that they once had a romantic relationship.
It was in the year 1990, while on a client’s assignment (finding a lost cat) in Episode One that Rin encountered Kouki. It seemed that Kouki was actually a clone of himself, the work of Sayara Yamanobe, a renegade scientist searching for the secrets of immortality, and needed Rin's help.
With it, Rin was able to get Kouki the answers he needed, and was hired on at the firm until Kouki's death in 2011, when he became an angel to rescue Rin from Sayara, who with Apos' help became an immortal. But Kouki's legacy would aid Rin later on, in the form of his son Teruki and his granddaughter Mishio.
Rin is extremely beautiful, attractive, pheromonal, and charismatic. She has amazing wavy hair, emerald green eyes, and flawless smooth fair skin. Her body is well-developed, well-endowed, nicely toned, and perfectly proportioned. She is capable of turning heads just walking down a street. Attracting the attentions of both men and women, although she usually dresses in a casual manner that won't attract much attention.
Overall, Rin doesn't take herself too seriously, except in dealing with Apos, or his hired lackey Laura, who would torment her for the better part of 65 years. She has a good sense of humor, and would often wave-off Mimi's all-too serious efforts to take her job seriously. She likes to drink, too, but would like Mimi to give her water when she asks for it... not vodka, as Mimi always does. She also enjoys nightly conversations with Tajimamori, who would call her regularly on the telephone, although Rin was oblivious of the fact that he was the person she first saw a millennium before.
She is very kind, compassionate, loyal, humorous (and can be quiet flirty and sometimes lightly sadistic). Rin is someone who always looks toward the future with a smile, even after a thousand years she still enjoys life to the fullest, has a very high value of life and has not developed an ego despite all the horrors she has seen. But she is also very pragmatic and is capable of killing someone without feeling any guilt or regret if it is absolutely necessary.
She is an excellent detective, with amazing observational/deductive/reasoning prowess, and has an eidetic memory. She is an excellent judge of character and possesses a skill called cold-reading; being able to tell when she is being lied to, knowing who she can trust, allowing her to easily and perfectly read & predict people and animals (manipulate them although she rarely does). Her judicious and loyal personality has allowed her to make life-long loyal friends, family and lovers.
Over the centuries, Rin had developed her skills to become an excellent fighter. She possesses enhanced; adaptability, speed, strength, reflexes, senses, dexterity, flexibility, agility, durability, stamina, endurance, memory, balance, tolerance, self-control, tactical/strategic analysis sense, analytical skills, calculation skills, wisdom, eloquence, business/finance/economic/management and leadership skills, luck, beauty, pheromones, and charisma. She possesses endless willpower, will to live, and vitality. She has timeless beauty. She is a quick learner, and has an infinite capacity for learning She usually disdains the use of firearms but wouldn't hesitate in using them if the opportunity presents itself. She also has a punch booster that uses shotgun-like shells that kill quickly. She has perfect immortality, she does not age or get sick, she doesn't need to eat, drink, or breath, and she will rapidly, perfectly & completely recover/heal/regenerate from any physical, mental, and spiritual damage.
Rin would rather use edged weapons over firearms, such as small daggers she can hide in various places on her body. She also has a chain garrote, which she can use to disarm or kill her opponents. She's also an excellent martial artist, and can do the same unarmed. She is also very skilled in stealth missions and sneak into places easily.