
Shirai Ran, an ordinary nurse, lost her life in an earthquake disaster and was reincarnated into an imperial world. There, she used her knowledge of modern medicine to heal the sick, and was revered as a goddess with special powers. The prince of Sekkakoku, Kuryu, who had heard the rumors, kidnaps her to "become my wife and cure me"!? As the potential next emperor, he is suffering from a mysterious illness… However, while she was only meant to be a temporary consort until she cured Kuryu's illness, she was soon overwhelmed by the supposedly cold-hearted prince's naturally doting love!? A reincarnation harem fantasy in which modern medicine is used to heal the ills of the palace. (Source: Novema, translated)
Koukyuu Ihi Den is a Japanese novel of 508,584 characters, with 13,906 unique words and 2,347 different kanji. Its difficulty rating on Jiten is hard, 3.4 out of 5. The full vocabulary list ranks all 13,906 words by how often they appear, and you can study them on Jiten or download them as an Anki deck.
Here are some of the words that appear most often in this media, as well as a sample of its rarer vocabulary.