Under Yoshihara's guidance, Gutai explored radically experimental approaches, including outdoor exhibitions, performances, onstage presentations, and interactive works.

He was deeply impressed by the humanist idealism of the literary movement of Shirakabaha (White Birch Society), which also promoted post-Impressionist artists such as Cézanne, Van Gogh, and Renoir.

Facilitated by Kamiyama, Yoshihara met painters Seiji Tōgō in 1928 and Tsuguharu Fujita in 1929 during their stopovers in Kobe on their return from their yearlong stays in Europe.

[17] In 1938, together with other avant-garde members of Nika who were pursuing abstraction and Surrealism, Yoshihara founded the Kyūshitsukai (Room Nine Society), which organized its own exhibitions.

[18][19] Following the Japanese government's intensification of its war efforts in Asia in the late 1930s and its anti-communist and anti-liberal oppression measures, which also affected artists, Kyūshitsukai ceased all activities in 1943.

[21] After the end of World War II, Yoshihara immediately engaged in the rebuilding of the art scene and cultural life in the Kansai region and beyond.

Also, since around 1946 Yoshihara provided designs for posters, products and window displays, and murals, as well as for stage sets of operettas, dance, open-air concerts, theater and fashion shows.

He attended meetings of the Tensekikai (Group of Rolling Stones) led by philosopher Tsutomu Ijima, co-founded artists groups such as the Han-bijutsu Kyōkai (Pan-Art Association), the Nihon Avangyarudo Bijutsuka Kurabu (Avant-Garde Artists Club Japan) in 1947, the Ashiya City Art Association in 1948 (a local umbrella group that hosted its own local salon, Ashiya City Exhibition), and the Nihon Absutorakuto Āto Kurabu (Abstract Art Club Japan) and Āto Kurabu (Art Club) in 1953.

[23][24] Together with artists such as Shigeru Ueki, Kokuta Suda, Makoto Nakamura, in 1952 Yoshihara founded Gendai Bijutsu Kondankai (Contemporary Art Discussion Group, commonly known as Genbi), an interdisciplinary forum for Kansai-based artists, critics, scholars and experts to engage in interdisciplinary thematic discussion sessions and joint exhibitions.

Among the participants were painters, sculptors, industrial, product and fashion designers, photographers, and in particular avant-garde artists from the traditional arts, such as calligraphy, ceramics, and ikebana, which encompassed members of Bokujinkai (Ink People Society), Sōdeisha (Running Mud Association), Shikōkai (Four Plowmen Group), and the Ohara, Sōgetsu, and Mishō ikebana schools.

In addition, Yoshihara participated in roundtable discussions of Bokujinkai and the Ohara school, contributed texts and illustrations to their publications (including Bokubi), and benefitted from the artistic exchanges they hosted with European and US-American abstract painters such as Pierre Soulages, Jackson Pollock, and others.

Adapting to these unconventional formats, the Gutai members, including Yoshihara himself, explored radically experimental methods of production and presentation, involving performative, ephemeral, and interactive elements.

[29] In his teaching, Yoshihara would refer to sources from his extensive library of around 6,500 art-related publications[30] that he had collected over the years and included numerous foreign-language art catalogues and magazines.

[31] He also urged his members to never imitate other artists and to always "create what has never been done before.”[32][33][34] Yoshihara's global ambition took a more concrete form when Gutai began its international collaboration with the French art critic Michel Tapié, the promoter of European Informel painting.

In 1958 Yoshihara travelled to New York to present a Gutai exhibition advised by Tapié at the Martha Jackson Gallery, and subsequently visited Europe.

For example, in 1952, his works were selected for the Salon de Mai in Paris the Pittsburgh International Exhibition of Contemporary Painting and Sculpture at the Carnegie Museum.

[40] In the years following the end of World War II, Yoshihara produced paintings depicting blurred human faces, bodies, and birds, with the fore- and backgrounds blending into one another, many of which were segmented by rigid grid of lines.

Around 1948, the human bodies and faces were increasingly distorted and fragmented into geometric forms, and with Yoshihara's reduction of the backgrounds to black monochrome surfaces, appeared archaic.

After 1950 Yoshihara continued to pursue this archaic, sandy and sign-like imagery with regard to the surface texture, now scratching the contour lines of his motifs into thick paint layers.

In his exploration of abstraction in these years, Yoshihara drew inspiration from the expressivity of non-figurative children's art, Zen calligraphy and painting, particularly the works of the 20th century Zen priest Nakahara Nantenbō, which Yoshihara saw at the Kaiseiji Temple in Nishinomiya,[41] and his exchanges with the avantgarde-calligraphers Shiryū Morita and Yuichi Inoue in the early 1950s, and US-American abstract artists.

His most influential achievement is Gutai, which Yoshihara led and held together with his artistic instinct, organizational and strategic savviness for 18 years, and which became a fixture in Japanese as well as global art history.