Suddenly, parasitic aliens descended upon Earth and cleverly infiltrated humanity by penetrating the minds of the vulnerable. These rapacious creatures achieved complete dominance over their hosts and were capable of transforming into various forms to capture their prey. Shinichi Izumi, a sixteen-year-old high schooler, became one of the victims to this parasitic invasion but miraculously, his brain remained unscathed. Instead, the parasite took residence in his right hand, unable to relocate. Dubbed Migi, the alien was left with no choice but to rely on Shinichi in order to survive. Despite their difficult beginnings, the pair formed an uneasy alliance and braved threats from hostile parasites aiming to get rid of this new danger in their species.