Summary
The Head Researcher is an unnamed individual who lived and passed away centuries prior to the main narrative. Known by derogatory titles such as Idiot Inventor, Stupid Chief Engineer, or simply The Scientist, he was born in modern Japan before being sent to a distant-fantasy world as a Reincarnator to battle the Demon King of that era. Although he never appears in person during the present timeline, fragments of his life are revealed through the discovery of his research diaries.
