This is an interesting question because out of all the books I personally have read on Korea, none come to mind on the specific logistics behind (or the lack of) the removal of Japanese at the end of WW2. Off the top of my head, when I visited the Busan Modern History museum last year in November, I do recall saying a lot of the Japanese colonizers in Busan were forcibly removed. But I would be skeptical of that because I may be misremembering things of course.

However, I have read something that may hint what may have happened, at least in the Northern provinces. The book I am getting this is one written in Korean by Kim Sung-bo (김성보) called History of North Korea 1 - Experience of Nation-building and the People's Democracy 19451960 (북한의 역사 1 - 건국과 인민민주주의의 경혐 19451960). This book is intended more for the layman, and as such, it lacks a lot of the footnotes and references we expect in proper history books.

Regardless, it talks about how people reacted to liberation in the Northern provinces. The North during this time especially in Pyongyang had the highest concentration of Christians. Under Japanese colonization, Koreans were forced to adopt Shintoism and many shrines were built as a result. The book notes that while there were many ways in which Korean people unleashed their fury and anger built over the colonization period, the most common one was destroying these Shinto shrines (he does not mention any of the other ways). After the Japanese surrendered on August 15, news spread outwards from Pyongyang (the center of North Korea) and the reaction to the news seems to have been pretty immediate as the author writes that the burning of Shinto shrines spread all over Pyongan Province into Hwanghae Province by August 21. The author specifically notes that Koreans restrained themselves from direct violent actions towards the Japanese. Whether this claim is true or not, I do not know, but as far as the Northern provinces go, the author suggests that it was fairly quick and nonviolent process.