From 1954 to 1963 he exhibited actively all over Japan. Most of his work from that period, about 45 paintings, is in the permanent collections of the Osaka Prefecture Contemporary Art Collection, the Hyogo Prefectural Museum of Art, Kobe and The National Museum of Modern Art, Kyoto.

In 1963 Yasuo moved to New York City where he continued to paint, but also became involved in a broader scope of work. In 1966, Yasuo collaborated with a colleague, Isamu Kawai, to produce a performance piece at Judson Church, New York. Being in a period of skepticism about visual art and in particular about painting, he decided to take a hiatus in Japan and remained there for two years. While in Japan he did only one performance piece before returning to New York in 1970. In 1972 he started working in mixed media.

In the mid 1970’s he began working as a mask maker and costume props artist for the theater world, and continued to work in that field until his retirement in 1999. Doing major work for New York City Opera, Houston Grand Opera, Universal Pictures, Disney’s World on Ice, Ringling Brothers, numerous Broadway shows, and many projects over years for the Macy’s Thanksgiving Day Parade, he was respected and well known in the field.

During those years, while doing work for the theater, Yasuo continued to create a significant body of work in the fine arts. In 1988 he was invited to have a solo exhibition at the Osaka Contemporary Art Center and two pieces of work were acquired by The Tokushima Modern Art Museum, Tokushima.

In the period between 1993 and 2000 he was selected for group exhibitions at :
The Philip Briet Gallery, New York: A Dialogue
Hyogo Museum of Modern Art, Kobe: Art In Kansai
Takamatsu City Museum, Takamatsu; Yokohama Sogo Museum,Yokohama: Elvis + Marilyn: 2 x Immortal (extended Japanese Tour)
Texas Fine Arts Association: Transcending Limits: Moving Beyond Mainstream and Margin. This was a two year tour involving The Jones Center for Contemporary Art, Austin; Art Museum of Southeast Texas; Beaumont; Blue Star Art Space, San Antonio; Wayland Baptist University, Plainview; Bath House Cultural Center, Dallas.

In 1998 Osaka Prefecture held a retrospective exhibition, from the Osaka Prefecture Contemporary Art Collection, at Fumin Hall, Osaka: Yasuo Ihara: 1955 - 1963.

His current work has the pronounced characteristic of being understood contingent to its environment.