Kirk here with an update from Japan Today on the murder of the young researcher at Kumamoto University:

https://japantoday.com/category/crime/67-year-old-man-arrested-over-murder-of-kumamoto-university-researcher

The article says that the police have not indicated whether or not the suspect has admitted killing Narahara. The following TV report and other reports I saw on TV today say that he has admitted “abandoning a corpse,” the charge on which he was arrested. https://abema.tv/video/episode/89-93_s10_p5148