This particular Joker is Professional Level Crazy.
All his evil deeds took lots of money, time to plan out, purchase tools and equipment, a place to store the equipment. He had to study the train schedules, how to purchase certain acids in large quantities w/o attracting suspicion.
What a shame that during all stages of this horror, at no time did he stop and think: “This is crazy. I can’t kill these innocent people. What did they do to me?”
This does not appear to be a matter of ‘Mania’, a sudden quick flash of irrational behavior. Manic/Depression is sometimes treatable.
Nothing was spontaneous about it. Lock Him Up, Japan!!
I hope he is executed where he stands and left where he lies.