The Seven Demon's Tamer Novel

Ryder claims he is not an introvert, but rather someone who stays indoors out of fear—a self-imposed isolation until he contracts his beast. On a planet dominated by summoners, humans receive marks upon maturity from beasts of the Astral Shadow Plain. These marks come in five colors: brown, orange, red, black, and white. Ryder was chosen by a supreme demon monarch called the Dracogon, bearing the rare black mark with only a 0.5 percent survival chance during contraction. However, Ryder's contract caused an unprecedented catastrophe. He inadvertently opened a link between the Astral Shadow Plain and Terra, his home world, endangering all humanity. With no warning of when a breach might occur and unleash mindless creatures upon his planet, Ryder must now solve the crisis he created—alone, just as he caused it.