Actually Oldboy and Sympathy for Lady Vengeance are part of a a trilogy. https://en.wikipedia.org/wiki/The_Vengeance_Trilogy The first movie wasn't that great but still competent. My favorite of the serial killer movies is Confession of Murder (2012). Oldboy comes pretty close to that but Confession of Murder (2012) has action thriller elements that are close to John Wick level (but on a lower budget) and there is the mass media social commentary that has a touch of Black Mirror to it. It's almost like Gen Urobuchi was involved in writing.

Since I mentioned Gen Urobuchi here is something I've written about one of his works: https://steemit.com/entertainment/@vimukthi/why-and-how-you-should-watch-aldnoah-zero-review-analysis-love-letter-and-personal-thoughts