The plot, rich in the mix of murder and action, is set in modern and near-future Tokyo, and revolves around Rin Asougi, an immortal private investigator.

She is often being hunted down by an assassin named Laura who was hired by Apos, an angel who persecutes immortals and is the current guardian of the Yggdrasil.

During a search for a missing cat, Rin instead finds Koki Maeno, a young man with distorted memories.

In 2025, Rin ends up investigating a case involving Koki's son, Teruki, after he meets his long-term cyber girlfriend in reality.

It is revealed that the unknown man on the phone was Tajimamori, Rin's savior from a thousand years earlier, a former guardian of the Yggdrasil, and Apos' father.

[10][11] Mnemosyne is a six-episode television series of 45-minute episodes directed by Shigeru Ueda and written by Hiroshi Ōnogi.

The animation was handled by Xebec, but planning and production was shared with Genco, that also had a part in the original concept creation.

As Yggdrasil tries to merge with her, Rin consumes Koki's time fruit and his spirit helps her to break free.

He acknowledges that "it's difficult to honestly care about any of these characters" but its confusing and yet compelling aspects grasp the audience's attention.

He criticized the amount of violence and sex that resulted in exhaustion and unpleasantness that led to "the whole trashy appeal".

Tom Tonthat argues that Mnemosyne features animation which is memorable and tells a good story, with mundane cases spiraling into sinister plots that endanger humanity itself, but is also a clearly adult series due to the level of nudity and sex.

This is coupled with an engaging story and each episode representing a year of the timeline between 1990 and 2055, including different technological developments which either change characters or the plot.

He ends the review by stating that this anime does a good job of telling a story, a "guilty pleasure anime" for which you should give much thought to the "blood smoothie or angel sex", concluding it is a form of "supernatural film noir" worth a look at, although hindered by the "heavy use of shocking sex and violence".

On June 12, 2015, the Chinese Ministry of Culture listed Rin: Daughters of Mnemosyne among 38 anime and manga titles banned in China.