During his time with Jikken Kōbō, Takemitsu came into contact with the experimental work of John Cage; but when the composer Toshi Ichiyanagi returned from his studies in America in 1961, he gave the first Japanese performance of Cage's "Concert for Piano and Orchestra". This left a "deep impression" on Takemitsu: he recalled the impact of hearing the work when writing an obituary for Cage, 31 years later. This encouraged Takemitsu in his use of indeterminate procedures and graphic-score notation, for example in the graphic scores of "Ring" (1961), "Corona for pianist(s)" and "Corona II for string(s)" (both 1962). In these works each performer is presented with cards printed with coloured circular patterns which are freely arranged by the performer to create "the score".