Lake Toya is the sentient spirit inhabiting the wooden bokuto wielded by the protagonist. He manifests as a middle-aged man dressed in a black robe, a red scarf, and orange sunglasses, identifying himself as the Toyako Hermit. His dwelling is a dark dimensional space furnished with items including a fridge, a bed stuffed with adult magazines, and a trash can holding used tissues alongside fried cuttlefish remnants – odors he attributes solely to the cuttlefish.

Originating from a Hoshikudaki (a weapon forged from a ten-thousand-year-old extraterrestrial tree capable of cutting nearly anything), Lake Toya persists as the bokuto's spirit even when the sword breaks during intense combat. He transfers his consciousness to each replacement blade procured through television shopping, always demanding the inscription "Lake Toya" for continuity.

He actively attempts to mentor the protagonist, proposing ultimate techniques like the "Jumbolic Magnum" (a punch launching targets skyward while expelling bodily fluids), "Thigh Burst" (a shin kick inducing severe cramps), and "The Dogeza" (groveling before opponents). These lessons are consistently rejected in favor of conventional combat.

His background includes spirit parents: a mother sporting an afro and white beard, and a job-seeking father who wields the lethal "Jack Nicolle" technique, firing energy beams from his bald spot. Lake Toya also owns a pet that sheds copious curly hair and is established as a former classmate of Taikobou from *Hoshin Engi*. Personal habits involve collecting female figurine books stored under his bed.

In the 2013 film *Be Forever Yorozuya*, he interacts with a time-displaced version of the sword's wielder, reinforcing his persistent mentorship role despite the wielder's reluctance. His character design and function parody Zangetsu from *Bleach*, notably when the sword dispenses soy sauce in a manner visually echoing Zangetsu's energy attacks.