Every New Year's Eve, the train line that includes Harajuku station runs all night for people welcoming the new year with a shrine visit.
A large tank filled with kerosene was also found in the vehicle.
Police took a man in his 20s into custody and charged him with suspicion of attempted murder.
Eight people were injured in the incident.
NHK TV footage showed a small van with the entire front end smashed and officers and ambulance workers rushing to the scene.
Kusakabe reportedly told the police that he had planned his attack on the Meiji Shrine area, but had been deterred by massive road blocks in the area. A 19-year-old university student remains unconscious after being hit by the minicar shortly after midnight on the well-known shopping street in Tokyo's Shibuya Ward, which is normally packed with young shoppers and foreign tourists during daylight hours.
One witness told NHK it was a "ghastly scene".
One college student sustained serious injuries during the attack and was undergoing surgery, the police spokesman said.
Another 19-year-old man was slightly injured after Kusakabe allegedly struck him after getting out of the auto, the police said. As of 5 a.m. local time, most people had dispersed from the area, Kyodo reported.
The vehicle hit its first victim about 30m into the narrow street before knocking down seven more over the next 100m, the Sankei Shimbun reported.
A police spokesman said the driver had been detained but has not given out any further details on the identity of the suspect. It also attracts global tourists in large numbers.
Meanwhile in Germany, police have detained a 50-year-old man on suspicion of ramming his vehicle into a crowd of people after midnight on New Year's Eve at a crowded plaza in the north-western town of Bottrop. There is no major fireworks display and no central point where revelers gather to see in the year.