The age of the demons has begun. Dr Faust has foreseen this rise of evil. Unfortunately, he is near death and is unable to personally battle this upcoming threat. Faust entrusts a young boy, Shingo Yamada, to take the responsibility of ridding the Earth of this new evil presence. Faust finds a birthmark on Shingo's forehead that signifies that he is the chosen demon fighter. Faust summons from hell what may be humanity's only hope of surviving: a less than enthusiastic devil named Mephisto rises. After signing a pact in blood to save humankind, Shingo and Mephisto set out to battle the supernatural world. (Source: AniDB)

The anime follows a group of friends Giulia, Maria, Enrico, Lucio and Angelon during the disaster as they team up with a Japanese journalist Shiro Ando, and begin their own investigation of what's occurring (during the week long period of exposure when the ICMESA refused to notify citizens of the poison). As many animals are dying and people are getting sick. The children and Shiro discover deadly dioxin was released and inform Enrico's father, the town mayor, who evacuates all the citizens. Shiro continues investigating more and learns of the negligence of La Roche, a company who controls ICMESA. La Roche knew they were in violating of existing safety laws/protocols and destroyed evidence of their crimes. The children attend a press conference to ruin La Roche's reputation as the destroyed proof might not be enough in a court of law to punish them. Giulia's pregnant sister, who opted to not abort, gave birth to a healthy girl. The happiness is short lived, as the baby prematurely dies from dioxin poisoning.

After the mysterious disappearance of one of its participants, the battle meant to name a successor to God is brutally interrupted, leaving behind a trail of destruction and shaking the world. Twelve years later, while the former contestants in the divine competition struggle to fit in society after they were turned into semi-permanents—beings unable to age—Lall refuses to let go of her brother, who has been forgotten by everyone. Determined to resurrect her brother—the only one she sees fit to sit on the heavenly throne—Lall steals her his cellphone from a cult run by a past competitor, which accidentally restarts the competition. Helped by her classmate Eko Sasaki, Lall will show no mercy to prevail against her enemies in her efforts to finally see her brother again.

The anime adapted from the manga remake version of the Korean webtoon "A Simple Thinking about Bloodtypes" involving the faceless and nameless characters of four different blood types to discuss about popular anthropomorphized blood types (the stereotypes about the blood types) in Japan and Korea.