Kumatarō Kido and Yagorō Tani

Kumatarō Kido (城戸 熊太郎, Kido Kumatarō; c.1857–1893) and Yagorō Tani (谷 弥五郎, Tani Yagorō) were Japanese spree killers who killed 11 people, including an infant, on May 25, 1893, a spree known as Kawachi Jūningiri (河内十人斬り). They committed suicide after the murders, and their remains were discovered on June 7.

Source: Wikipedia — Kumatarō Kido and Yagorō Tani (CC BY-SA 4.0)