Entei makes his first appearance in Chapter 294 "Entei" and in episode 141 titled "Entei the Demon Horse Unleashed."
Entei initially shows up before a formidable ogre demon named Rengokuki, who wields a naginata and easily fends off hordes of demons with sheer willpower. Impressed by his strength, Entei offers his servitude to Rengokuki, and together they become a feared duo. Later on, this demon is subdued by a powerful holy seal, which is subsequently destroyed by Hakudoshi. Reuniting with his former partner, Entei engages Inuyasha's group in battle but only manages to hold them off briefly before retreating. He later encounters Hakudoshi and challenges him, yet finds himself unable to even scratch him. As the "battle" drags on, Entei begins to doubt Rengokuki's power and eventually tosses him off his back, rejecting his old master and accepting Hakudoshi as his new one. The demon is then beheaded, and Hakudoshi takes his weapon as a prize.
From that point forward, Entei is ridden by Hakudoshi for all future appearances until he is ultimately defeated by Inuyasha's Backlash Wave.
