Kuroi Ransuke

21st Century, Tokyo. People called “challengers” are gambling their life trying to escape from the state-owned 100 Story Tower to win 10 billion yen. But what will happen when Tatsuki Kuroumi awakes at this tower without remembering anything about his prior life, including entering the tower as challenger?

Mamoru, a mediocre college student, discovers an item of darkness while searching for the missing father of his childhood friend, Yuuka. This item is a "human card" which can trap people on a single sheet of paper for buying and selling.

Day laborer Kazuya Shibuya is feeling frustrated with his boring, day-to-day life when a mysterious game called “Blackout” is delivered to him out of the blue. Not knowing what is going on, he starts to play the game, only to find out that what is inside surpasses anything he could have ever imagined. No one has ever managed to beat this game shrouded in mystery. Is “death” awaiting him at the end…?

The story follows a young man named Kazuya Shibuya who receives an anonymous email message out of the blue one day: "Won't you join the Savanna Game?" The message is an invitation to a state-sanctioned killing game — a deadly role-playing game designed to motivate the inhibited youth of modern Japan. Shibuya and his two friends Kotegawa and Kudou find themselves in bizarre battles that span the space-time continuum, with everything from dragons to the Shinsengumi force of the shogunate era.