A girl goes back in time and realizes that just maybe time travel wasn’t a thing for a reason as she messes up more and more of her life. When what seems to be an oasis in the form of her Principal arrives, she thinks everything could end up okay, only to later find out he planned to find and torture the time traveler until she gave him her blueprints. It was a good thing he just thought she made for a good assistant and didn't know she was said time traveler… Right?

Old summary:

Time travelling to the past, May didn't expect to be trapped in her younger body. Forced to relive her life, her attempt to speed through school is halted by her odd and criminally insane principal, whom she calls the Master. Turned into his assistant, she tries surviving even as her own actions make everything worse. With a principal that had never been there previously and her home life slowly becoming more and more abusive, May is slowly dragged into angst as the weight of what she's caused settles on her shoulders.