She is an immortal female private investigator who runs her own detective agency in Tokyo. 

who likes standing-up for others and is very kind, compassionate, loyal, humorous (and can be quite flirty and sometimes lightly sadistic)

she is also very pragmatic and is capable of killing someone without feeling any guilt or regret if it is absolutely necessary

Rin became infected by what was called a Time Fruit, which made her immortal.

She is fine with both men and women.