Akihabara massacre (June 8, 2008)
Refers to the indiscriminate killing incident that occurred in Akihabara, Tokyo, on June 8, 2008. Used as a proper noun for this specific event.
The Akihabara massacre occurred on June 8, 2008.
A compound of 秋葉原 (Akihabara), 無差別 (indiscriminate), 殺傷 (killing and wounding), and 事件 (incident). The term was coined to refer to this specific event.