Spirit Tamer

Spirit Tamers use their hearts as bait to lure spirit clans from across the heavens and put them to work. This is the story of a sickly Spirit Tamer armed with a game guide from his previous life, who first recruits history's weakest starter spirit and then carries a split-personality world-destroying demon king on his back, signing contracts with all kinds of problem children along the way and growing into the strongest young (Spirit) Care (Tamer) Center (Master) in the Wild Spirit Continent [not really]. A sickly, scheming bottom with a built-in blood-spitting buff x a split-personality late-stage rabid dog / tsundere top. The daily life of a Spirit (Beast) Tamer (Trainer) and a split-personality tsundere / rabid dog.