Prosecutors on Tuesday demanded the death penalty for a 40-year-old man accused of killing his roommate's two sons in Tochigi Prefecture.
Akihiro Shimoyama's actions constituted "a contemptible and cruel crime committed to save himself" from the discovery that he was abusing the two boys, the prosecutors told the Utsunomiya District Court.
Shimoyama, 40, an unemployed resident of Oyama, pleaded guilty to the murders as well as to consuming a stimulant drug prior to the crime.
Shimoyama is accused of throwing Kazuto Kobayashi, 4, and his brother Hayato, also 4, off a bridge in Oyama into a fast-flowing river, where they drowned in the early hours of Sept. 12.
The boys and their father, Yasunori Kobayashi, who was later sent to prison for using stimulants, were living in Shimoyama's apartment.
Shimoyama and Kobayashi are both divorced fathers and have known each other since childhood. They went to the same junior high school.
According to the prosecutors, Shimoyama killed the boys because he feared their father would find out he had struck the pair the day before the murders.
Shimoyama routinely beat the children because he was unhappy that he had to live with them and because Kobayashi did not pay any of their living expenses, the prosecutors said.
Shimoyama's counsel called for leniency, arguing he was in a state of diminished responsibility at the time because he was under the influence of the stimulant.