Yamachichi (Yamajijii)

The provided sources do not supply a substantive traditional origin narrative for Yamachichi in classic primary folklore texts. Modern summaries and fandom/game pages report two related ideas: that Yamachichi is a mountain-associated yōkai (implied by the kanji 山) and that some commentators or modern retellings describe it as arising from aged animals (notably aged monkeys) or as a possible evolutionary/formal relation to Nobusuma-type animal-spirits. These latter claims appear in contemporary wiki/fandom material and should be treated as reported interpretations rather than established classical origin myths in the supplied corpus.

Descriptions of Yamachichi's form in the available materials come primarily from modern game/fandom sources, which portray it as apelike or a large monkey-like humanoid. The short encyclopedic (Wikipedia) entry lists the name and classifies it as a yōkai but does not give iconographic detail; thus the apelike description reflects modern retellings rather than documented traditional iconography in the provided notes.

Behavioral and ability-attribution for Yamachichi in the supplied materials is chiefly recorded in modern fandom and game wikis. These sources describe a nocturnal predator that invades sleeping humans (including travelers) and 'sucks the souls out of sleeping travelers via their mouths' or otherwise feeds on victims' life-force. One account adds that if a victim does not wake, the spirit taps the chest and the person dies within a day; conversely, if feeding is interrupted by the victim waking, that source reports the victim's life may be magically extended. The short encyclopedia entry confirms the yōkai classification but does not provide these narrative mechanics; therefore the detailed feeding mechanics are attested mainly in contemporary secondary sources.