Kawaei was never able to fully mentally recover and in next year's March announced her departure ("graduation") from the group giving her psychological inability to attend fan "handshake" events anymore as the reason.

[2] The weapon used by Umeta was a foldable handsaw that he had found and taken from his home, modifying it by attaching boxcutter blades on its side.

[2] He kept the weapon concealed in a handbag which he carried with himself into the tent booth where the members were located, and drew it out upon entering inside.

[8][9] Reports by the prefectural police at the time of the incident says he declared that he "felt frustrated after losing his job the previous December",[10] and that for him "anyone was good for killing",[11] saying he eventually opted for an AKB48 handshake event because a large number of people would be gathered in one place.

[12] Two different AKB48 CD singles were found during an early house search;[13] Umeta asserted in court he first inspected the venue using the event ticket from one, before he would go on to commit his attack,[14] choosing what booth had the shortest queue to strike faster.

[9] At the trial, Umeta denied injuring the male staff in the November 2014 session,[8][9] but eventually pleaded guilty to charges of bodily injury and infringement of weapon regulations in December.