An emergency call was made around 3:45 p.m., reporting an attack by a student at Hosei University's Tama Campus in Machida, reported Japan's Kyodo news agency.
According to reports, the attacker was identified as a 22-year-old South Korean woman.
She was subdued and arrested.
Investigative sources quoted the suspect as saying she was "frustrated" after being ignored by a group of students and used a hammer she found on campus, Kyodo news agency reported.
All eight people sustained minor injuries.
This was a rare incident of violent crime in the country.