8.1 - Yamada Yuusuke Gekijou

8.1 - Yamada Yuusuke Gekijou is a manga written by YAMADA Yuusuke and illustrated by U.G.E

Plot
There is a mysterious group of people who inflict cruel and fatal games on people for their own amusement. Tatsuya and Misa are out on a date in an amusement park when they wander into one of these horrific competitions on the tallest roller coaster on earth. The seats fall out of their 12-person roller coaster car, and they are told that the game will end when all but one person has fallen to their death. Will the passengers be able to find a way to escape the competition? Will there be any retribution against the orchestrators of this sick crime?

Other Sources

 * MyAnimeList