Tsukiko Sagi, a shy character designer who created the immensely popular pink dog Maromi, finds herself under pressure to repeat her success.

Soon the attacker, dubbed Lil' Slugger (Shōnen Batto in Japanese, meaning "Bat Boy"), is blamed for a series of street assaults in Tokyo.

[3] During the makings of his previous three films (Perfect Blue, Millennium Actress, and Tokyo Godfathers), Paranoia Agent creator Satoshi Kon was left with an abundance of unused ideas for stories and arrangements that he felt were good but did not fit into any of his projects.

The site's critical consensus reads, "Anime auteur Satoshi Kon brings his feverish vision to the serialized form in Paranoia Agent, a disturbing meditation on individual and societal anxiety.

[17] Charles Solomon from NPR says, "Paranoia Agent may frustrate viewers who expect a straightforward narrative, but it's a disturbing, highly original work from a talented filmmaker.

[21] Jean-Luc Bouchard from BuzzFeed praised Paranoia Agent as a depiction of depression, writing, "The entire series totals a mere 13 episodes, but it drew me in immediately, and introduced me to a dark cast of characters whose troubled minds changed not just their own perceptions, but each other's realities as well.

A haunting and deeply felt fable of human experiences told with Satoshi Kon's signature flair, eerie and funny in equal measure, visuals that will stick with you for years to come".

[23] A review for IGN gave the first three episodes of Paranoia Agent a score of 7/10, comparing it to the works of David Lynch, but criticizing the animation as "downright primitive in places".

[24] John Maher from Paste listed Paranoia Agent as the 14th best anime series of all time, comparing it to Kon's other works Paprika and Perfect Blue, adding, "it's every bit the sublime exercise in psychological thriller as either".