Looking for a title

I thought of this hentai I remember reading a while back but I can't for the life of me remember the title. It was about people who traveled through time enforcing rules and their necklaces would display their emotions above their heads. It was Vanilla so I'm hoping fellow army members can help me out here.

Was it Akai Mato's Liberator Series?

Thank you. It was driving mad trying to remember the name. My hero.