Aquino wins over a wide spectrum of Japanese audiences. She packs the house at a church, a business lunch, a university

``The real challenge,'' Corazon Aquino said, ``is to achieve peace by the ways of peace.'' Throughout her visit to Tokyo this week, the Philippine President is conscious that she is talking to many audiences. They include her official Japanese hosts, certainly, and influential businessmen, but also the general public - especially young people, among whom her popularity far out-ranks that of Prime Minister Yasuhiro Nakasone.

Nor can she forget that she is talking to her own people during an important crossroads in Filipino history. Will a cease-fire with the communist insurgents be achieved? Can the spirit of national unity and ``people's power'' that catapulted her into the presidency be preserved?

Yesterday, Mrs. Aquino started her day in worship with Japanese and Filipino Christians at St. Ignatius Church. She went on to meetings and lunch with Japan's leading businessmen, and then to receive an honorary degree at Waseda University, where Robert Kennedy also appeared 25 years ago. She varied her remarks to suit her audience, but the fundamental theme everywhere was the same - peace and reconciliation.

``We do not face each other and see the nemesis of our fathers and grandfathers,'' she told the congregation at St. Ignatius. ``We do not keep the grudges of the past,'' she said, referring to Japanese atrocities in the Philippines during World War II. ``The future is ours to build together.''

At the lunch with businessmen she said, ``Remember that the backbone of [our] revolution was the business class. Call them unlikely revolutionaries, but then our revolution was unusual. It was not done to overturn society but to restore democracy.''

For the Waseda students, who packed the university auditorium while more than 5,000 more waited outside, she referred to her negotiations with the communists. ``Some people say I am naive to have done this. I can only say that I owe it to our people, who have lived in fear of the gun for so long, to exhaust every means with reason to give them the peace they so much deserve.'' She used Japan as an example: ``You never achieved so much in war as you have now done in peace.''

Aquino began her speech at Waseda by recalling that she started out being a simple housewife, much like most Japanese women. Japanese wives serve their husbands' guests tea. Mrs. Aquino served them coffee. ``Some of these friends of [her husband] are now my ministers. They do not talk about the times when I served them coffee,'' she observed dryly. ``Today I am No. 1, not only at home but over the country.''

Waseda is one of Japan's top private universities and is the country's only academic institution with a program in Philippine studies. Students formed a People's Forum Committee to collect signatures on a petition to have Aquino visit Waseda, and committee members went to Manila in September to take their plea directly to the presidential spokesman. So there was a special warmth when student representatives gave Aquino a bouquet of yellow roses and the whole auditorium burst into singing the school anthem.