Both of the following are revenge stories that take place regarding events from high school. The only real difference is one is Adult vs High schoolers and the other is Adult vs Adult after high school

Both of the female leads are righteous and fight against wrongful actions. Into the ring falls more into politics while Saito-San is more of a neighbourhood. Both have shows of the female leads getting another person to join them in their journey and a strong bond of community. You`ll end up loving the side characters in both.

It has a very similar vibe with serial killers, characters with traumatic backgrounds, everything is a mystery, even aired similarly. The only thing different was that they investigated other cases too, Plus, it has Jang Hyuk who is always a must-watch xD