There is a lot of evil in the Japanese justice system. They will bully people into confessing to crimes they didn't commit just to keep up their 99% conviction rate, torture people in terrible ways during those interrogations, and be completely arbitrary in how they carry out those executions. Such as rushing 3 executions out within a week of an unrelated massacre just to save face.

Problem is, that's both complicated, nuanced, and would be difficult for a lot of people to fully criticize.

So instead they fall back on the good ol' "death penalty bad!" or the even dumber "its so barbaric" even though lethal injection (the most "humane" in their eyes) is the most brutal execution we have minus that its cleaner.