Kenpeitai was a group of people who worked for the Japanese government a long time ago. They were like police officers, but also had special jobs like spying, arresting people, and punishing them. They were really strict and made people follow very strict rules.
If you lived in a place controlled by the Kenpeitai, you needed to be very careful not to break any of their rules, otherwise you could get in big trouble. They punished people who did things that they didn't like, and sometimes their punishments were very cruel and mean.
Kenpeitai was not a good thing, because they made people live in fear and didn't let them be free. Many people were hurt by them and didn't like how they acted. Today, we have better laws and people who protect us in a fair way, so we don't need the Kenpeitai anymore.