During a ritual by a divine being in a parallel realm, Eiji Choukai is whisked away to a different world. Surprisingly, the god only offers him the unique 'Parasite' Class, unlike the myriad options in typical reincarnations. Disheartened yet compelled to make do, Eiji embraces this fate. To his amazement, he discovers the incredible potential within this seemingly limited Class. Harnessing the parasitic abilities, Eiji unlocks the capability to exponentially enhance his own strength by assimilating the powers of others. With this newfound power, Eiji treads a precarious path where his escalating level might lead to unforeseen consequences.