Diabolo (manga)

 is a Japanese manga series by Kaoru Ohashi and Kei Kusunoki. It was serialized by Shueisha from 2001 to 2003.
Plot.
"Diabolo" revolves around teenagers in Japan being converted to followers of the "Diabolo" by a secret society, in exchange for the fulfillment of their wishes. Teens who have made a pact with the Devil begin to go crazy at age 17, often manifesting in acts of brutality and homicide, and upon turning 18 reach a point of no return to their original selves. The phenomenon is a mystery to the adult world and media, who try to ascertain the origin of mass teen violence. There are six great spirits (also teenagers) that serve the Devil, each of which has a hand in destroying the world. The main characters, Ren and Rai, use their own Devil-given powers to stop them while searching for their cousin Mio, saving other teenagers from their pacts, and racing against their approaching 18th birthdays. It describes its plot as "The age where the ensured bend to temptation and slowly fall from human to devil." 
Characters.
Six Great Spirits.
All six of the Great Spirits' names are taken directly from the hierarchy of hell as listed in The Grand Grimoire. They are teenagers who have adopted the names of the Great Spirits following their pacts with Diabolo and the acquisition of their powers. They are the primary antagonists for Ren and Rai.
Release.
"Diabolo" was written and illustrated by twin sisters Kei Kusunoki and Kaoru Ohashi, and 3 volumes were published by Shueisha from 2001 to 2003. It is published in French by Soleil, and was published in English by Tokyopop in Northern America.
Reception.
Liana Cooper of Anime News Network criticised the first volume for being episodic. However she felt it started off "pretty exciting". In Jason Thompson described the "visuals and action scenes are weak".