Suspect entered a convenience in Kawaguchi City and held a knife up to a female cashier in September
Body likely belonging to Natsuki Taniguchi, 20, was found in the back seat of a rental car in a parking lot in Iwaki City
Victim was transported to a hospital in a conscious state, police said
Defendant said upon his arrest in September, 'I wanted to enhance euphoria throughout my entire body'
Tokyo police believe the suspect carried the body of his girlfriend out of her residence in Nerima Ward on December 3
Examination of her body revealed that she appeared to have been strangled around the neck by a cord, police said
Suspect told police, 'I entered the unit to try to kill people'
Suspect allegedly smashed a beer bottle over the head of a male employee and stabbed him in the face with a glass shard
Marugen Group manages buildings nationwide that house hostess clubs and bars