Tokko

is a horror manga series written and illustrated by Tohru Fujisawa. It was serialized in Kodansha's Afternoon in 2003 and collected into 3 tankōbon volumes. The manga was later licensed in North America by Tokyopop on July 15, 2008. An anime adaptation produced by AIC Spirits and Group TAC, premiered in Japan on April 15, 2006. The anime was then licensed in the North America and United Kingdom by Manga Entertainment on March 20, 2007. The anime made its North American television debut on the the Syfy Channel's Ani-Monday programming block on June 18, 2007.

Plot
Officially known to the general public as Special Mobile Investigation Forces Section 2; Special Public Safety Task Force, or Tokko under the supervision of the Public Security Intelligence Agency after the Special Mobile Investigation Troops relinquished, with some of its members recruited from the police force. It was established after the Machida massacre was secretly investigated to discover that the perpetrators were demons, called Phantoms, from the netherworld, able to cross into reality when the "Box of Dirge" (or "Druj", as the DVD English subtitles say) was broken, with each of the 108 pieces being taken by a powerful Phantom. Under the command of Superintendent Ryoko Ibuki, she recruited members, who, as survivors of the Machida massacre, have Phantoms inside them that when "awakened", grant the superhuman speed and the ability to materialize swords. They use swords to dispatch the Phantoms and their lesser human faced larva parasites, that come into the world through the giant holes caused by unnatural earthquakes in Japan's Kanto region, since most firearms do not incapacitate or kill them. Their actions have come under harsh criticism from other officers for conducting their operations in secretive manners and for covering up the deaths of either civilians or police officers, informing the public via news releases that deaths or injuries caused by demons were done by armed or insane criminals.

All members of Section 2 bear a tattoo (except for Ibuki who is not a symbiont). This is their "symbiont tattoo", which marks them as carriers of a "phantom", one of the 108 demons. Not all of the symbionts are with Section 2. A symbiont may be good or evil, but the spirit's alignment is unknown until it is awakened within the host. This phantom also imparts a type of protection, for example allowing Sakura to walk away unscathed from a car accident as a child. Only symbionts have the strength, speed and endurance to kill the demons with bladed weapons. Using the symbionts, Section 2 hunts down the other Phantoms, dismembering them to get the 108 fragments to close the Machida hole before it expands and covers the entire world. (Source: Wikipedia)

Other Sources

 * WOWOW's site for the anime
 * Manga UK's site for the anime
 * Wikipedia
 * Mangaupdate
 * Anime News Network
 * Anime News Network