Biwamaru, a blind wandering monk and former samurai, carries a lute concealing a hidden blade. Clad in tattered robes and wielding a cane, his disheveled guise masks a sharp spiritual perception: he discerns the "color of souls," sensing malice and spectral forces—a gift paralleling Hyakkimaru’s. This sight guides his role as a moral compass, steering others through ethical quandaries and unseen threats. Once a warrior, Biwamaru renounced violence to wander in penitence, battling demons and healing the afflicted. His shadowed samurai past lingers unspoken, hinted only through his disciplined bearing and knowledge of combat. Embracing acupuncture as his craft, he treats without charge, rejecting invasive procedures—a stance that sparks rivalry with surgeon Black Jack, though both share reverence for the artisan who forged their tools. As a mentor, he challenges Hyakkimaru to weigh the cost of reclaiming his stolen body, cautioning that slaying demons might unravel fragile societies. With Dororo, he adopts a gentler tone, urging her to honor her parents’ memory and wield their hidden wealth wisely. Their bond deepens in later tales, where Dororo’s concern for his welfare mirrors her journey from thievery to empathy. In *Black Jack*, Biwamaru emerges as a principled healer, clashing with surgical methods yet acknowledging Black Jack’s skill. These divergent narratives weave him into a bridge between eras—a penitent warrior-physician navigating duty, redemption, and the pull of human bonds. Though initially distant, later stories reveal his growing attachment to those he aids, culminating in his covert role toppling the Daigo regime—a quiet nod to the life he once abandoned.