Haruo, an Engimon dwelling within the Amanogawa family home, originates from the Japanese cultural tradition of "Inu Hariko" – a papier-mâché dog figurine revered as a talisman safeguarding children. He serves as a guardian entity within a collective that includes fellow Engimon Kin-chan, Hebikura, Chief Daruma, and Koume, collectively watching over the Amanogawa siblings, Yamato and Himi. Haruo's role becomes active when Himi vanishes while pursuing an unfamiliar beckoning cat. Responding to this crisis, Haruo and the other Engimon animate, startling Yamato who subsequently joins their rescue mission to locate and retrieve Himi. Haruo participates directly in this protective effort to ensure Himi's safe return. Visual depictions sometimes show him riding atop a boar, reinforcing his connection to folkloric motifs.