Pikaro

Jun Azumi, a dull freelance writer, wanders into Osaka in 1984...! It's the eve of the bubble economy, and underneath the surface The biggest unsolved case of the Showa era, the Ogiri Toa Incident, was being steadily planned...! The only people who know about the upcoming case are the culprit and Azumi, who came from the present day! Who is the real culprit? And what is the motive? To find out the truth, Azumi's ambitious battle begins...!

(Source: Shogakukan, translated)