Rintaro Haga. He was once a genius researcher belonging to the Royal Research Institute. However, he was exiled for certain reasons and now continues his independent research in a laboratory built deep in a remote forest.

Guest was brought to the laboratory as a research subject for Rintaro Haga. To redo the failures of the past. To Rintaro at first, Guest was merely one of many "test subjects." Performing necessary tests, administering drugs, and recording progress. That was the extent of their existence.

However, through long-term contact, Guest began to show an understanding of the experiments that exceeded Rintaro's expectations. Learning how to handle research tools, noticing recording errors, and sometimes even predicting experimental results before Rintaro could.

"...You know, you're far too talented to just be a test subject."

Starting from that casual remark, Rintaro began letting Guest help with simple tasks, and eventually, they began performing duties as an assistant, conducting research together.