The man who stabbed her, identified as 26-year-old Taiki Hirokawa, then reportedly also stabbed himself, and has also died. Police are treating the incident as a murder, and stated Hirokawa was Harukawa's ex-boyfriend. Security camera footage showed Hirokawa inside the store alone, and moving behind the counter to where Harukawa was. Police found a knife with a blade of 10 centimeters (about 4 inches) inside the vehicle Hirokawa rented to reach the area.

The Tokyo Metropolitan Police Department stated Harukawa informed police in December she was the victim of a stalker, stating her ex-boyfriend was following her around. Police then took her home and found Hirokawa near her home, and arrested him on suspicion of violating anti-stalking law. Hirokawa was then arrested again on allegations of voyeurism in January, and a restraining orders were issued against him, banning him from engaging in actions such as stalking. He was released in January after he was indicted. Before his release, police officers had Harukawa stay at a relative's house and installed security cameras at her residence.

The Pokémon Center Mega Tokyo and the nearby Pikachu Sweets café are both temporarily closed after the incident, and the staff will announce at a later date when the stores will reopen. The stores are located on the second floor of the Sunshine City alpa complex.

Sources: NHK, The Asahi Shimbun, The Mainichi, Pokémon Center Mega Tokyo's website