I've Been Killing Slimes for 300 Years and Maxed Out My Level (スライム倒して300年、知らないうちにレベルMAXになってました; Slime Taoshite 300-nen, Shiranai Uchi ni Level Max ni Nattemashita) is a 2017 light novel series written by Kisetsu Morita, with illustrations by Benio. It was adapted into a manga by Yusuke Shiba.
Azusa Aikawa died at age twenty-seven from overwork, just five years after getting her job. When a goddess offers her a second chance with a bonus, Azusa chooses immortality, and is reincarnated as a 17-year-old witch in a fantasy land. She becomes the medical practitioner of the Flatta village and kills low-level slimes for magic loot, becoming very powerful after 300 years. She takes on apprentices and discovers the feeling of family she had missed out in her previous life.
- Blob Monster: Slimes.
- Level Grinding: Without realising it, Azusa grinded her way into level 99 by killing slimes and selling magic stones. It did take her 300 years to do it, though.
- Long Title
- Mana:
- This is a fantasy world, after all.
- The goddess specifically reincarnates Azusa in a body with mana circulation so that her immortality would be possible.
- Meaningful Rename: Azusa chooses to call her own name in katakana instead of kanji, to better fit the fantasy world and to differentiate her second life.
- Really Seven Hundred Years Old: Invoked by the goddess, who chooses to make Azusa immortal at seventeen.
- Salaryman: Azusa's job in her previous life.
- Tragic Dream: In her previous life, Azusa dreamed of sightseeing in Switzerland, but she died before she could go there.
- Translation Convention: Azusa can read and understand a language that isn't Japanese.