Korean has a number of words for "yes". 예 (ye) is highly polite and formal (appropriate in an interview), 네 (ne) is polite but less formal (appropriate in a conversation with parents), and 응 (eung) and 어 (eo) are plain and non-formal (appropriate in a conversation with friends).
Native Korean word, from reconstructed Old Korean*yeli(“Japanese”). First attested in Hangul form in the Yongbi eocheon'ga (龍飛御天歌 / 용비어천가), 1447. Replaced by Sino-Korean terms in all modern dialects.
Hyeseong-ga, an Old Korean or Early Middle Korean poem in the hyangchal orthography, writes the Korean word for "Japanese" as 倭理. In hyangchal, native Korean nouns are written by a sequence of two Chinese characters, the first glossing the semantic meaning of the word and the second representing the final syllable or coda consonant of the Korean word. 倭理 must thus be read as a native word with the final syllable *-li. A sound change from a bisyllabic form with the final syllable *-li into a diphthongized monosyllabic form through loss of /l~r/ is well-attested in Korean (see e.g. 내 (nae, “stream”)), and the Old Korean form of Middle Korean 예 (Yale: yey) can accordingly be reconstructed as *여리 *yeli.
The gradual decline of this native exonym for the Japanese can be seen in the Ildongjangyuga, a Korean-language vernacular poem composed by an emissary to Japan in 1763. This work uses the term yey seventeen times and the Sino-Korean term 왜 (倭, woay) forty-nine times.