I’ve Been Killing Slimes for 300 Years and Maxed Out My Level - Recommendations

Alt title: Slime Taoshite 300-nen, Shiranai Uchi ni Level Max ni Nattemashita

If you're looking for manga similar to I’ve Been Killing Slimes for 300 Years and Maxed Out My Level, you might like these titles.

Seichou Sokushin to Ganbou Cheat de, Isekai Tensei Slow Life? (Light Novel)

Seichou Sokushin to Ganbou Cheat de, Isekai Tensei Slow Life? (Light Novel)

Rucalt was reincarnated as the second son of an aristocrat after saving a girl from a runaway truck and dying. God bestowed upon him a cheat ability that allowed him to gain any skills he wished for. In addition, he could easily level them up with just a bit of use. By the age of three, he had gained the strength unparalleled that of all heroes in history. Nonetheless, he did not flaunt his powers, instead choosing to lead a life of freedom happily with his family in this other world!

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By the Grace of the Gods

By the Grace of the Gods

Slime's up for one recently deceased middle-aged businessman! When the gods reincarnate him in another world as a boy with magical powers, he discovers that magically-tamed slime are an untapped natural resource! Upon his sudden death, middle-aged otaku businessman Ryoma Takebayashi finds himself in a curious situation. Three gods request his cooperation in their divine plot, which requires him to reincarnate in another world as a young boy! Equipped with magic, young Ryoma undertakes a carefree existence in the forest, leisurely learning more about his new abilities and surroundings. And when he encounters slimes like those in video games from his former life, Ryoma uses his newfound magical powers to get creative with his research! Will the gods get more than they bargained for in Ryoma?!

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Tensei Kenja no Isekai Life: Daini no Shokugyou wo Ete, Sekai Saikyou ni Narimashita

Tensei Kenja no Isekai Life: Daini no Shokugyou wo Ete, Sekai Saikyou ni Narimashita

Yuuji Sano, a black company employee, is summoned to another world while finishing his work at home. His profession in the other world, a Monster Tamer, is considered a job that makes it difficult to become an adventurer. However, thanks to some slimes he met, which read several magical books, he gained magical powers and the second profession, Sage. Yuuji acquired overwhelming power, but is he conscience of his strength? Blindly becoming unparalleled and strongest in the world!

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Saijaku Tamer wa Gomi Hiroi no Tabi wo Hajimemashita.

Saijaku Tamer wa Gomi Hiroi no Tabi wo Hajimemashita.

Ivy's daily life is anything but the peaceful, ordinary childhood enjoyed by other children. She possesses memories of a past life in another world, and at five years old, she learns to her parents' shame that she only has one low-level skill: taming extremely weak slimes. Unwanted by her family, she begins living in a nearby forest, learning to survive on her own with the help of her village's local fortune-teller. But when Ivy's "starless" existence is blamed for the old woman's misfortune a few years later, the child is forced to flee to avoid being killed. She journies from town to town collecting discarded items and selling what she can, until one day Ivy encounters a rare slime that she names Sora. What adventures await the young girl and her slimy new companion?

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Saikyou Juzoku Tensei: Majutsu Otaku no Utopia

Saikyou Juzoku Tensei: Majutsu Otaku no Utopia

I, who should have died after being hit by a car, was born again in another world. However, I was born in a shady minor family that used magic and controlled wooden puppets called the Marren Clan. Possessing a strong interest in magic since my previous life, I spend my time zealously studying magic to the point where even the people in the vicinity draw back. One day, I heard I was to be married to my little sister when I turned 16 in accordance with the traditions of the Marren Clan and decided to flee to the city. For now, since I have the strongest magic, I guess I should idle around making only enough money so that I don’t have to work for my whole life.

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Level 1 no Saikyou Kenja

Level 1 no Saikyou Kenja

One day, Kijou Haruto was forcefully transmigrated and cursed by a god from another world. A world of swords and magic. In this world you get stronger by increasing your battle levels. But due to a curse, Haruto is unable to gain levels. However, due to a mistake by the Evil God, Haruto was able to obtain an inexhaustable supply of magic...

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Homeless Tensei: Isekai de Jiyuu Sugiru Jikyuu Jisoku Seikatsu

Homeless Tensei: Isekai de Jiyuu Sugiru Jikyuu Jisoku Seikatsu

Shinichi Tanaka used to be a representative director of a large company, but now he is homeless without money or family. On a rainy day he is struck by lightning and awakes in a strange place in the body of his younger self. What is the mysterious place he finds himself transmigrated into? A weird and turbulent adventure story of a 56-year-old man who reincarnates into a different world in his 25-year-old body!

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Akuyaku Reijou Level 99: Watashi wa Urabosu Desu ga Maou de wa Arimasen

Akuyaku Reijou Level 99: Watashi wa Urabosu Desu ga Maou de wa Arimasen

I reincarnated into the "Villainess Eumiella" from an RPG Otome game. In the main story, Eumielle's merely a side character, but after the ending, she reenters the story as the Hidden Boss, a character on par to the Heroes with her high stats!! Lighting a fire in my gamer's soul, and taking advantage of being left on my own in my parent's territory, I train! Train! And at the end of my training... By the time I enter the academy, I managed to reach level 99. Though I had planned to live out my days as inconspicuously and peacefully as possible, soon after entering the school, I'm suspected by the Heroine and Love Interests of being the "Demon Lord"...? 

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Isekai de Mofumofu Nadenade Suru Tame ni Ganbattemasu.

Isekai de Mofumofu Nadenade Suru Tame ni Ganbattemasu.

After various things happened, I got an ability from God and reincarnated to another world! While being watched over by my high-spec family, the super ordinary me fully enjoyed other world life. Using the ability I received from God, I had a daily life of just fluffing and petting fantasy animals. There are some shady movements too, but while being led by the nose by God, I’ll do my best at various things with my cheat-like comrades!

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Level 1 no Saikyou Kenja (Light Novel)

Level 1 no Saikyou Kenja (Light Novel)

One day, Kijou Haruto was forcefully transmigrated and cursed by a god from another world. A world of swords and magic. In this world you get stronger by increasing your battle levels. But due to a curse, Haruto is unable to gain levels. However, due to a mistake by the Evil God, Haruto was able to obtain an inexhaustable supply of magic...

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