The first robin of spring has

been sighted in these parts,

and his name is Sadaharu Oh. He was spotted in Manhattan a few days ago, ostensibly to promote his glorious autobiography, ''A Zen Way of Baseball,'' but doing more to teach a few writer types how to turn their hips on an inside pitch.

There is something cosmically revitalizing on the coldest day of the winter to be ushered into a small reception and receive a batting tip from a man who hit 868 home runs. It seemed restorative to him, too, as he raised his right leg in the familiar flamingo style and pointed to the spot on his right hip where all his left-handed power had come from.

He reassured us all that his team, the Tokyo Giants, would soon be heading for spring training on the island of Guam, in a seaside camp. He became manager last season, having retired as a player after the 1980 season, but he did not teach his one-legged batting stance to any of his players.

Most American baseball fans are aware, at best, that Mr. Oh (he refers to his teammates and opponents as ''mister;'' it seems impolite to do less for him) surpassed the home-run totals of Babe Ruth and Henry Aaron. But no American can know Sadaharu Oh until he or she reads ''A Zen Way of Baseball,'' published by Times Books and written by David Falkner, a writer and actor from New York who was mystically matched with Mr. Oh in Zen-like circumstances.