TOKYO — Young John Rockefeller, scion of America's multimillionaire family, is a "big man on the campus" near here.

But it isn't because of his family's millions.

He stands on an academic pedestal at International Christian University because he is a part-time teacher of English there.

"TEACHING IS about as high as you can get in Japan," the 20-year-old exchange student said.

Rockefeller is on a two-year "leave" from Harvard University for a study of written and spoken Japanese at the school in Musashino.

"I give the students English lessons and the school gives me the right to stay here," he said. He pays tuition, board and other expenses.

AT THE MOMENT, Rockefeller is attempting to step down from the pedestal — or, as he explains it, to "disassociate from the staff level" — by moving out of his "ivory tower" faculty apartment into a Japanese style boarding house with eight other students.

Rockefeller sticks close to the campus, going by train to Tokyo only two or three times a month "to see a movie or talk to friends."

"Study is the thing here," he said. "Social life you can discount, and I'm willing to do that."

HE PLANS to finish at ICU in August, 1959, and then go back to Harvard for his senior year. He thinks he will then spend two years in the Army.

"I hope I can teach or interpret Japanese over here," he said.

WHEN HIS service days are over, he wants to study for five or six years at Harvard-Yenching a famous school of Oriental studies.

"My interests are definitely in the Far East," he said. "I want to learn as much language and culture as I can during my stay."

The youth's father is John D. Rockefeller III, chairman of the board of the Rockefeller Foundation, which has given millions of dollars in world-wide philanthropies since John D. Rockefeller Sr. — the student's great-grandfather —founded it in 1909.

THE FAMILY fortune, comes from oil interests.

Student Rockefeller will inherit the middle name Davison and the numeral IV when he becomes 21 next month.

"Dad and I wanted it that way," he said. He will also become financially independent but isn't sure about the amount of money he will get.

"IT DEPENDS on a trust fund and I'm rather hazy about the details," he said.

His father, president of the Japan Society and the Asia Society, Inc., will come to Tokyo Monday for an 11-day visit.

But young Rockefeller isn't clear about his father's plans here.

"I HAD HIS itinerary for a day and lost it, so I don't know what he's going to do," he said.