This work was composed in 1972 for the pianist Aki Takahashi.

The piece begins with a rapid repetition of the single note F, gradually expanding into tremolos of minor seconds and diminished thirds, subtly varying in pitch, dynamics, and tempo. While there are irregular and dissonant single-note passages marked "as fast as possible," there are also passages that demand the simultaneous performance of irregularly arranged note sequences by the right and left hands, for example, as quadruplets and quintuplets, or sextuplets and octuplets. Occasionally, violent chords, like sharp incisions, resound at fff. This acoustically tense work literally demands every possible technique and concentration from the performer on the keyboard.

Why did the composer insist on such a parade of highly advanced techniques? In fact, this work contains "a protest and irony against the almost complete rejection of inside-piano techniques in Japan at the time" (composer's words). Inside-piano techniques refer to methods such as directly touching the piano strings or inserting bolts or rubber between the strings to produce sound (John Cage's prepared piano is a famous example). In the 1970s, when this piece was written, there was intense conflict in Japan between concert halls, which managed pianos as equipment (and thus opposed inside-piano techniques), and composers, who sought new sonorities. This piece, born from Yuasa's "irony" of strictly limiting the performance to the keyboard, can in a sense be considered a historical product.