Global Beastmasters: From the Start, I Contracted a Ghost

A meteor streaked across the sky, and the era of cataclysm quietly dawned. Evil beasts invaded, and humanity's armies could barely hold them back. Thankfully, the immortal human race managed to crack the method for making pacts with spirit beasts. The age of beast taming quietly arrived across the globe. But while everyone else tames beasts, I tame ghosts. Something about that just seems a little off...