Myriad Colors Phantom World (無彩限のファントム・ワールド, Musaigen no Fantomu Wārudo) is a Japanese fantasy light novel series written by Sōichirō Hatano and illustrated by Shirabi.

The series, set in the future Kamigyo ward, an accidental release of an unstable virus caused an epidemic that alters the human brain, leading to the creation of the beings called “phantoms”.

In the near future, the accidental release of an experimental virus causes an outbreak that changes the brain chemistry of every person in the world, allowing them to perceive extra-dimensional beings called "Phantoms".

After Haruhiko treats Reina to lunch in the high school cafeteria, he explains that the Alayashiki Company's research facility was hit by a terrorist bomb over a decade ago, releasing a virus that infected the human brain.

Those with special abilities established club-like groups within their schools in order to seal and expunge troublesome Phantoms for a reward.

After Haruhiko introduces Reina to Mai, the three of them set off to deal with wooden Utility Pole Phantoms called Tsukumogamis, which are causing radio disturbances.

Arisu assigns Haruhiko, Mai and Reina to assist Koito Minase, a newly transferred student who first manifested her special ability of her singing voice at a young age.

They are requested to go to the Alayashiki Company's abandoned factory, where there have been reports of a Security Robot Phantom causing a disturbance by controlling drones.

Arisu soon assigns Haruhiko, Mai and Reina to deal with a strange UFO Phantom that peeps on the college girls in their dormitory.

While Mai and Reina lure the UFO Phantom by wearing towels, Haruhiko eventually implements his Parole by summoning a sketch of Marchosias using a cut on his finger.

With Arisu's help, Haruhiko and Mai visit an amusement park, a movie theater and a climbing gym among other places in order to synchronize shared memories, though Reina expresses jealousy.

Arisu assigns Koito to deal with a Dragon Phantom attacking the school chicken coops and rabbit hutches.

Upon meeting Kurumi Kumamakura at the primary school division of Hosea Academy, Koito encounters the Dragon Phantom, but it renders her special ability useless.

Just as Haruhiko, Mai and Reina arrive to help, Kurumi uses her special ability of transforming her inanimate teddy bear Albrecht into an animate fighting giant, causing the Dragon Phantom to flee.

Haruhiko concludes that they are stranded in an alternate world created from Kurumi's memories centered around bears, including the animal itself, her favorite food, her birthplace and her surname.

Meanwhile at the Neural Error Corrections Room, Koito tells Mai and Reina that Kurumi is capable of fighting but needs to get over her mental hangups.

At the high school, the students unknowingly begin behaving like cats, notably long naps and fish cravings.

Under the sweltering heat, the high school grounds have transformed into a hot spring guarded by an adult male Monkey Phantom.

Several students including Shosuke, the Beach Angels, Mai, Haruhiko, Kurumi and Koito each fail in their attempt to seal the Monkey Phantom.

A mock wedding is held in order to cheer up the Monkey Phantom, and Haruhiko plays the unfortunate role of the bride.

Ayumi Kitajima, the sole member of the Drama Club, eventually convinces Haruhiko, Mai, Reina, Ruru, Koito and Kurumi to participate in the regional competition for her play loosely based on the Ikedaya incident.

In the middle of the play, Ayumi is revealed to be a Bakumatsu Phantom, who was manifested from the suppressed rage and frustration of losing the regional competition for ten straight years.

Ayumi then transforms the stage into an illusion of the scenery around and inside Ikedaya Inn, while the audience members serve as extras.

Heading to the fireworks festival dressed in yukata, Natsuno feels guilty when Haruhiko, Mai, Reina, Koito, Kurumi and Arisu all desire for Ruru to be there with them.

During the fireworks festival, Haruhiko bandages Natsuno's sore feet while confiding in her that he wants Ruru to be there with him even though she is usually troublesome.

With summer vacation right around the corner, Haruhiko, Mai, Reina, Koito and Kurumi have the highest grades compared to the other teams in the Phantom-hunting Club.

The Sea Monster Phantom appears and emits a mist at the students, creating an optical illusion of nudity with a polka dot phenomenon.

When Haruhiko summons Marchosias and Chtulu in order to repel the effect of the polka dot phenomenon, the Sea Monster Phantom gets angry and emits a mist again, creating another optical illusion of nudity with white censor bars this time.

As the students can finally enjoy summer vacation, Haruhiko makes it back to shore after being swept by the wind waves caused by the girls.

Mai, Reina, Koito and Kurumi run away in embarrassment, while Haruhiko loudly expresses that he hates summer, even though Ruru likes it.