Glimpsing an elderly man leading his blind daughter on a pilgrimage, Junoshin Kakiri, a 'ronin' or freelance samurai, swiftly kills him with a sword. Asked why he murdered such an innocent, Junoshin shares his concerns about the growing 'Harahuhi Tou' (Belly-shaking Party) cult to which the man was devoted, a fear which rapidly spreads through the Kuroae clan. Shuzen Oura, the warlike leader of half this kingdom, soon hires Junoshin to destroy the cult but his studious power rival, Tatewaki Naito, cunningly pays the mercenary samurai to usurp Oura on his behalf. Set in Edo-period Japan, 'Punk Samurai Slash Down' follows the power struggles which entangle Junoshin within the Kuroae clan, polarizing the kingdom between an academic leader unable to fight and an unlearned martial arts expert.