Top 10 Strongest Contracted Beasts in Isekai Anime, Ranked

The worlds of Isekai anime are filled with mythical beasts and powerful familiars – it’s more than a common theme for the reincarnated heroes (or villains sometimes) to be in a contract with these beasts who aid them in battle or simply become their companions. That being said, some of them are extremely strong.

While there are hundreds to choose from, we narrowed it down to the top 10 we think fit the powerscaling at the very top. Without any further ado, here is our interpretation of the strongest contracted beasts in the world of Isekai anime, ranked by raw power, feats, and narrative impact.

10 Sylvie – The Beginning After the End

Don’t be fooled by this tiny little munchkin, Sylvie from The Beginning After the End is actually the daughter of Sylvia and descends from the powerful Indrath Clan, making her one of the most extraordinary bonded beasts in Isekai.

She is a powerful Basilisk-Dragon hybrid and Arthur Leywin’s loyal soul-bond – possessing immense strength, spatial manipulation, and the ability to shift into multiple forms, including her iconic “little black fox/cat” form and her massive draconic battle form.

9 Mio – Tsukimichi: Moonlit Fantasy

Another instance when looks can be absolutely deceiving. Mio from Tsukimichi: Moonlit Fantasy is actually the Black Spider of Calamity. In her form as the Black Spider of Calamity, she is a giant purple-black spider with a sinister aura; 8 very large, strong, and hard legs capable of destroying and piercing concrete foundations and even normal metal.

She has a plethora of abilities – from devouring incoming attacks to poison immunity to healing abilities – everything that makes her a powerful contracted companion for Makoto Misumi.

8 Tio Klarus – Arifureta: From Commonplace to World’s Strongest

Tio Klarus is an Elder Dragon of the Klarus clan, ancient and immeasurably powerful, who willingly joined the protagonist Hajime Nagumo’s party in Arifureta: From Commonplace to World’s Strongest. While she holds the voluptuous human-like look that can easily fool spectators, her draconic physique gives her monstrous endurance and physical strength, while her breath attacks level terrain and shatter fortifications.

She is a very essential member of Hajime’s party, serving primarily as a healer. But when needed in combat, her enthusiasm in battle is matched only by her genuine, formidable power.

7 Tomoe – Tsukimichi: Moonlit Fantasy

Tomoe was the first companion to join Makoto on his journey in Tsukimichi: Moonlit Fantasy, one of the best seasonal anime from its time. Tomoe is a powerful Greater Dragon existing in the World of the Goddess, the Mirage Dragon, who contracts with Makoto after an intense battle of wills – a fittingly dramatic beginning for one of the series’ most capable characters.

She wields spatial magic at an elite level, can create entire pocket dimensions, and possesses an almost obsessive love of samurai culture and Japanese history. In combat, her illusion and space-manipulation abilities make her extraordinarily difficult to pin down.

6 Jet – Reincarnated as a Sword

Jet, or Urushi, is a Wolf magic beast familiar that was summoned by Teacher, the main protagonist of the Reincarnated as a Sword isekai anime series. Jet was summoned by the Teacher and accompanied Fran, the young beastkin warrior at the series’ heart.

Although he was introduced relatively early, Jet proves his worth time and again with explosive speed, fierce close-range combat ability, and unwavering loyalty –  his dark-type attributes synergize well with Fran’s own fighting style, and his growth trajectory suggests he is far from his ceiling.

5 Night (Yoru) – My Status as an Assassin Obviously Exceeds the Hero’s

Night is a Black Cat beast – a species already feared for its magical lethality – who bonds with Akira early in the My Status as an Assassin Obviously Exceeds the Hero’s series. Deceptively small and unassuming, Night possesses extraordinary stealth capabilities and assassination-oriented combat skills that perfectly complement his contractor’s own talents.

What made him even scarier was his ability to shapeshift and change his form to resemble the demon Cerberus – the more power Night uses, the more he resembles Cerberus. He grows alongside Akira at a frightening pace, and his dark-attribute magic makes him especially lethal against enemies relying on light or holy power.

4 Ranga – That Time I Got Reincarnated as a Slime

As the son of the Great Dire Wolf, Ranga pledged absolute loyalty to Rimuru Tempest in That Time I Got Reincarnated as a Slime after his father’s defeat and never looked back.  He evolves rapidly throughout the series, eventually becoming a Star Wolf of staggering power – capable of shadow travel, devastating storm-based attacks, and near-instantaneous movement.

However, it’s not entirely his powers that make him iconic; it’s his unwavering loyalty towards Rimuru. Among contracted beasts who serve a single master, few are as reliably overwhelming on the battlefield.

3 Filo – The Rising of the Shield Hero

Filo wasn’t just a companion to Naofumi Iwatani in The Rising of the Shield Hero; she hatched from a monster egg and was under Naofumi’s care from the moment she was born, imprinting on him. What starts as a simple filolial chick rapidly evolves into something far beyond ordinary – she transforms into an angelic, winged form that even the Filolial Queen recognizes as extraordinary.

Her speed is almost unmatched in the series, and her physical power levels rival those of heroes and waves of calamity – yet she’s cheerfully unaware of just how terrifying she is, somehow making her more endearing.

2 Fel – Campfire Cooking in Another World with My Absurd Skill

The Campfire Cooking in Another World with My Absurd Skill is a very laid-back and relaxing Isekai anime series; no one expected to see an extremely powerful beast in that series until they saw Fel. Fel is an ancient Fenrir – a divine beast of legend who has roamed the world for thousands of years, effortlessly overpowering gods and monsters alike.

Despite contracting with the utterly ordinary Mukouda, Fel’s power remains completely unchecked – his wind and lightning magic is god-tier, and his sheer magical reserves make her virtually unkillable.

1 Veldora Tempest – That Time I Got Reincarnated as a Slime

The Storm Dragon Veldora Tempest is one of the four True Dragons – ancient, cataclysmic beings whose very existence warps the world around them- and Rimuru stumbles on him as the first creature he meets after being reincarnated in That Time I Got Reincarnated as a Slime.

Sealed for centuries, his bond with Rimuru Tempest is as much a brotherhood as a contract – once freed and reborn with a human-like form, Veldora unleashes destruction at a scale few can comprehend. For a simple scaling purpose, his roar alone reshapes battlefields, and his raw magical output dwarfs nearly every other being in his world.

RANKING	CHARACTER	ANIME SERIES	IMDb RATINGS (as of June 11, 2026)
1	Veldora Tempest	That Time I Got Reincarnated as a Slime	8/10
2	Fel	Campfire Cooking in Another World with My Absurd Skill	7.6/10
3	Filo	The Rising of the Shield Hero	7.6/10
4	Ranga	That Time I Got Reincarnated as a Slime	8/10
5	Night (Yoru)	My Status as an Assassin Obviously Exceeds the Hero’s	6.6/10
6	Jet	Reincarnated as a Sword	7.3/10
7	Tomoe	Tsukimichi: Moonlit Fantasy	7.7/10
8	Tio Klarus	Arifureta: From Commonplace to World’s Strongest	7/10
9	Mio	Tsukimichi: Moonlit Fantasy	7.7/10
10	Sylvie	The Beginning After the End	5.8/10

What are your thoughts on our ranked list of the strongest contracted beasts in the Isekai anime genre? We’d love to hear your top picks and your opinions on our list in the comments below.