Sometime prior to the first chapter, Mitsumi received Infernape when it was a Chimchar from Professor Rowan. Professor Rowan gave her Chimchar to teach her that Pokémon were her friends. Chimchar then witnessed Feebas’s evolution into Milotic. Sometime later, it evolved into Monferno and then into Infernape.
In Team Galactic's Ultimate Warrior, after Hareta found out that Mitsumi is a member of Team Galactic, Infernape snuck behind Hareta and sent him crashing to a wall in order to force him into a battle. Infernape then threw Byron into a Warp Panel. As Hareta and Mitsumi began their battle, Infernape began with a Focus Blast which was aimed at Regigigas and then followed up with Close Combat as the smoke occurred. However, Infernape ended up hitting Kadabra instead of Regigigas as Kadabra’s Skill Swap allowed it and Regigigas to switch Abilities, giving Regigigas a chance to escape on the ceiling.
In Clash! Hareta vs. Mitsumi!!, Hareta was about to use his Onix against Infernape but Leafeon defeated it before he had the chance to do so. Infernape was then shown defeating Hareta's Lucario. It then roasted Hareta with Fire Spin. As Hareta was about to have Luxio use Thunder, Infernape emerged from underground and quickly defeated Luxio. After Hareta was down to Piplup, Regigigas, and himself, Infernape attempted to strike Piplup but Hareta blocked Infernape’s attack and then had Piplup use Hydro Pump, taking it out.
In A New Battle Begins!, Infernape was the first Pokémon sent out against Cynthia where it went up against her Garchomp Both sides used Overheat and Giga Impact and then were substituted for Electivire and Lucario, respectively. Infernape was sent out again later in the match where it used Focus Blast on Garchomp. As Garchomp dodged, the Focus Blast strayed over to where Koya was but he was able to protect himself with Metagross.
Infernape was shown to have a strong bond with Mitsumi, as evidenced with its time in the Master Rank of the Pokémon Super Contest. When Mitsumi reverted back to her time as a member of Team Galactic, Infernape went along as it took orders without any hesitation even though its time as a Chimchar and Professor Rowan's teachings was what led Mitsumi into treating Pokémon as friends instead of tools.