The publication of a new dictionary titled The Great Passage progresses. Mitsuya Majime, originally from publisher Genbu Shobo's sales department, has been recruited by Kouhei Araki, a veteran editor of the dictionary department who is looking to retire soon. The dictionary department is known internally as the "money-eating insect," but Mitsuya uses his perseverance and attachment to the words in order to become a great editor. Mitsuya, who has poor social skills, finds himself working with another man named Masashi Nishioka, who is able to express himself better.
During the Japanese occupation of Korea, the Japanese Empire seeks to eradicate the Korean language and identity. In retaliation, a small group of Korean patriots try to protect their language by compiling the first Korean language dictionary.
Professor James Murray begins work compiling words for the first edition of the Oxford English Dictionary in the mid 19th century, and receives over 10,000 entries from a patient at Broadmoor Criminal Lunatic Asylum, Dr. William Minor.