NHK and local news agency Jiji reported that one child has been confirmed dead after the attack. The attacker also reportedly died from a self-inflicted wound.
Earlier, NHK broadcaster reported that an unidentified attacker stabbed 15 people in the Japanese city of Kawasaki near Tokyo, three of them were in critical condition, including one child.
According to the Kyodo news agency, an unknown 50-year-old man stabbed 19 people at a bus stop.
The attacker stabbed himself, suffering a serious wound, NHK said. The broadcaster added that two knives were spotted at the scene, but there was no immediate confirmation from officials.