I've Been Killing Slimes for 300 Years and Maxed Out My Level

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.

Tropes used in I've Been Killing Slimes for 300 Years and Maxed Out My Level include:

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.