The Amakusa murder case is truly messed up, tke killer is a fucking idiot who somehow didn't realize there is no money left of his target. Even though his daughter still got saved by the blessing of real treasure, the idiot will still be looking on 4 capital murder charge. That's either death penalty or life imprisonment, the idiot will never be able to be with his daughter. In other hand, Itsuki lost his only chance of happiness, and 20 years later he is still by himself instead of being married with 3 kids. Truly the 2nd of 3 most tragic cases.
This Yukikage murder case, some probably think it's tragic. Perhaps it is, but this case can be summed up to the killer's grievance which breaks out in anger blaming someone else for it. The dead girl Haruna can be said to be half responsible for it. Her rash decision making would end up causing 4 tragic death. And the killer's own conscience to be completely destroyed forever. I guess I can say this is one of 9 stupid idiot case of being too dumb to live.
However the next case after this, Russian doll murder case is the creme de la creme of good versus evil. Kindaichi vs Takato. The victims death is nothing more of casualty along the way. their death is really tragic and yet for the killer, it was not personal. The killer have no resentments toward the victims but still the killer kills them. In a way this case is what it means of "THE BAD GUY WINS". as there is nothing the law or Kindaichi can do about it. All Kindaichi can do is to reject what Takato said of the nature of evil.
PS: seems like gentdude skip the " Student Akechi Music Orchestra case". It shows off Akechi multi talented skill. The case itself is nothing exceptional. But it is heartwarming to see old friends are still there.