Conqueror of Flames

Conqueror of Flames (爆炎の支配者) is the seventh episode of the anime adaptation of That Time I Got Reincarnated as a Slime.

Synopsis
Shizu dreams about her past; about when she was summoned by Leon and he had Ifrit possess her. She recalls the anguish she felt when the Ifrit residing inside her killed a new friend she made and little monster they named together after she and Leon were considered enemies by the monster. Later, just as Shizu prepares to leave Rimuru's village with the adventurers, Ifrit once again takes control of her and unleashes his flames upon the village. With his water attacks proving ineffective, Rimuru copies Elen's ice magic spell to take care of Ifrit's minions. Discovering that he is immune to fire attacks, Rimuru swallows Ifrit, separating him from Shizu in the process. Now Ifrit lies trapped in Rimuru's stomach where he encounters the monstrous being known as Veldora Tempest.

Plot
One day, shortly after being summoned to the new world and bonded to Ifrit, Shizue Izawa and her summoner/master are attacked by the "Great Sorcerer" Koenig. Deciding to treat the situation as an opportunity Leon has his newly minted minion incinerate the bird man. Satisfied Leon asks the girl her name and decides to call her Shizu.

After Shizue's injuries have been treated she starts wandering around the nearby forest where she encounters a young girl named Pirino who has befriended an orphaned fox monster that Shizue names Pizu who grows bigger as a result. Deciding that the monster seemed friendly the two bring him back with them to Leon's castle as their pet.

Unfortunately Pizu becomes openly hostile to Leon and as a result Ifrit takes over Shizue's body and incinerates both the monster and his owner leaving Shizue severely traumatized. Waking up from the nightmare the adult Shizue finds herself in The Goblin Village where Ifrit's aura is now acting up. Though Shizue likes the town her quest to track down her summoner lures her elsewhere, that said Rimuru states she's welcomed back at any time.

On her way out of the village, Ifrit finally breaks free from Shizue's control and takes over her body and goes on a rampage. Rimuru Tempest orders the goblins to evacuate and confronts Shizue with Cabal's Party, with the adventurer's realizing that Shizue is really a veteran hero also known as the Conqueror of Flames. To combat his enemies Ifrit summons several Salamanders to fight alongside him.

Though Rimuru's water blade attack is initially ineffective against the fire spirits he mixes it with Elen's Icicle Lance attack to create the Icicle shot gun for use against the monsters. Once the Salamanders have been defeated Rimuru orders Ranga to take the Adventurer's away to safety. Confronting Ifrit alone Rimuru is initially caught in a trap when he's consumed in a flare circle by Ifrit.

Although Rimuru initially freaks out Great Sage reminds him that he has Thermal Fluctuation Resistance which immunizes him against fire based attacks. Instead Rimuru uses Ifrit's own attack as a smoke screen to bind him in Steel Silk followed by swallowing him using Predator and separating him from Shizu. Once inside of Rimuru's stomach Ifrit is confronted by Veldora Tempest who laughs at Ifrit as he claims that he cannot defeat Rimuru.