The Paranoia Agent anime series features an extensive cast of characters created by Satoshi Kon. The series takes place in Musashino, Tokyo, focusing on the serial street assaults caused by an unknown assailant known as Lil' Slugger, and the numerous persons who are affected by them.
- Tsukiko Sagi (鷺 月子 Sagi Tsukiko) is a character designer and the creator of Maromi. She was Lil' Slugger's first victim.
Voiced by: Mamiko Noto (Japanese), Michelle Ruff (English)
- Maromi (マロミ Maromi) is a character created by Tsukiko Sagi who has accumulated a large degree of popularity among the masses. Maromi was modelled after a dog that Tsukiko owned in her youth.
Voiced by: Haruko Momoi (Japanese), Carrie Savage (English)
- Keiichi Ikari (猪狩 慶一 Ikari Keiichi) is the chief detective in charge of investigating the Lil' Slugger case. He is a tough middle-aged man with a critically ill wife.
Voiced by: Shōzō Iizuka (Japanese), Michael McConnohie (English)
- Mitsuhiro Maniwa (馬庭 光弘 Maniwa Mitsuhiro) is the detective assisting Keiichi Ikari in the Lil' Slugger case and doubling as his foil in personality.
Voiced by: Toshihiko Seki (Japanese), Liam O'Brien (English)
- The Mysterious Old Woman (謎の老婆 Nazo no Rōba) is a homeless woman who dwells near the scene of Lil' Slugger's attack on Tsukiko, of which she is a witness.
Voiced by: Hisako Kyōda (Japanese), Melora Harte (English)
- Misae Ikari (猪狩 みさえ Ikari Misae) is Keiichi Ikari's wife. She is seriously ill but, despite her illness, she wants to live. She is only person who can stand against and repel Lil' Slugger.
Voiced by: Kazue Komiya (Japanese), Melodee Spevack (English)
- The Mysterious Old Man (謎の老人 Nazo no Rōjin) is a senile hospital patient who possesses the ability to predict and identify all of Lil' Slugger's victims.
Voiced by: Ryūji Saikachi (Japanese), William Frederick Knight (English)
- Lil' Slugger (Shōnen Bat (少年バット Shōnen Batto) in the original Japanese) is an enigmatic serial assailant who appears to be a sixth-grade elementary student and is identifiable by his golden roller blades, baseball cap, and golden baseball bat.
Voiced by: Daisuke Sakaguchi (Japanese), Sam Riegel (English)
Lil' Slugger victims
- Akio Kawazu (川津 明雄 Kawazu Akio) is a reportage writer attempting to cover the Lil' Slugger case. He is indebted to the Old Man's son (voiced by Hiroshi Yanaka in the Japanese version and by Sam Riegel in the English adaption) after causing a traffic accident involving the Mysterious Old Man and is forced to pay his hospital bills as consolation. He becomes Lil' Slugger's second victim while attempting to interrogate Tsukiko Sagi and gather information for his next article. He is skilled in impressions and demonstrates this talent to Tsukiko by flawlessly mimicking her co-workers.
Voiced by: Kenji Utsumi (Japanese), Doug Stone (English)
- Yūichi Taira (鯛良 優一 Taira Yūichi) is a cool-natured and narcissistic elementary school student who lives near the scene of the original Lil' Slugger attacks. His personal tutor is Harumi Chōno, whom he is emotionally close to. He is initially popular due to his intelligence and athleticism, but because of his golden roller blades and baseball cap, he becomes associated with the recent Lil' Slugger attacks and becomes the subject of ostracism. Following Lil' Slugger's attack on Shōgo Ushiyama (whom he disliked for stealing his popularity), he secludes himself into his room and is reduced to a delusively paranoid state before becoming Lil' Slugger's third victim.
Voiced by: Mayumi Yamaguchi (Japanese), Johnny Yong Bosch (English)
- Shōgo Ushiyama (牛山 尚吾 Ushiyama Shōgo) is an elementary school student who transferred to Yūichi's school on the advice of his school counselor to positively assert himself. He does so by running for the office of school president. Yūichi believes Shōgo to be a two-faced schemer who is behind the current attacks on Yūichi's reputation to boost his own popularity, when in reality he is a kindhearted youth who seeks to better himself by being positive and helpful whenever he can. He becomes the victim of a Lil' Slugger imposter while on his way home from school.
Voiced by: Makoto Tsumura (Japanese), Steven Bendik (English)
- Harumi Chōno (蝶野 晴美 Chōno Harumi) is an office lady who works as a personal tutor for Yūichi Taira. Harumi possesses an alternate personality named Maria (まりあ Maria), who works as a prostitute. The two personalities communicate via an answering machine. After being engaged and married to her superior Akihiko Kase (voiced by Toshio Kobayashi and Lance J. Holt), Harumi repeatedly attempts to repress the manifestation of Maria, which proves futile. In the apex of her conflict with Maria, Harumi becomes Lil' Slugger's fifth victim.
Voiced by: Kotono Mitsuishi (Japanese), Erica Shaffer (English)
- Masami Hirukawa (蛭川 雅美 Hirukawa Masami) is a corrupt police chief who often watches his daughter Taeko undress through the use of a hidden surveillance camera. He attempts to have a new house built for his family using illegally obtained money to fund the project. He manages to arrest a Lil' Slugger imposter when an attack attempt is made on him. The house he attempts to build is eventually destroyed in a landslide brought on by a typhoon. He is fond of women and is a regular customer of the prostitute Maria. He later becomes Lil' Slugger's sixth victim.
Voiced by: Toshihiko Nakajima (Japanese), Deem Bristow (English)
- Makoto Kozuka (狐塚 誠 Kozuka Makoto) is a middle schooler under the impression that he is a holy warrior when he is in fact a lunatic unable to distinguish reality from his fantasies. He is arrested under suspicion of being behind the Lil' Slugger attacks. He later demonstrates to Maniwa how he supposedly carried out the attacks up to that point. He eventually becomes Lil' Slugger's eighth victim and is killed by the attack.
Voiced by: Daisuke Sakaguchi (Japanese), Sam Riegel (English)
- Taeko Hirukawa (蛭川 妙子 Hirukawa Taeko) is the only daughter of Masami Hirukawa. After discovering her father's foolish and disgusting actions, she becomes Lil' Slugger's seventh victim and contracts amnesia as a result of the attack.
Voiced by: Nana Mizuki (Japanese), Kari Wahlgren (English)
Internet Suicide Pact
Mellow Maromi Staff
The production staff of Mellow Maromi, an anime that features Maromi as the main character. The two most prominent members of the staff are the production managers, Nobunaga Oda (voiced by Daiki Nakamura and Frank Dallas) and Naoyuki Saruta (voiced by Hiroyuki Yoshino and John E. Breen).
- Masashi Kamei (亀井 正志 Kamei Masashi) is an otaku and a regular customer of Maria. He makes short appearances in the first and third episodes, as well as the twelfth.
Voiced by: Akio Suyama (Japanese), Jonathan C. Osborne (English)
- Junji Handa (半田 順次 Handa Junji) is a Yakuza member affiliated with Masami Hirukawa.
Voiced by: Daisuke Gōri (Japanese), Howard Clarendon (English)
- Shunsuke Makabe (真壁 俊介 Makabe Shunsuke) is a sadistic lackey of Junji Handa who attempts to collect 2,000,000 yen from Masami to give to Handa as a token of congratulations for his engagement. When Masami is unable to provide this amount within the given deadline, Makabe increases the debt to 5,000,000 yen.
Voiced by: Keiji Fujiwara (Japanese), Kirk Thornton (English)