Composed at the commission of Katsumi Ohtaka, this sonata was premiered at his recital. Although consisting of only two movements, it is the largest-scale sonata. The form of Beethoven's Sonata Op. 111 is consciously referenced. The first movement is a fast and secco movement, primarily based on musical ideas created by contrapuntally combining dynamically ascending and descending figures. The second movement is an Andante movement dominated by a fantastical tranquility, which can also be understood as a Passacaglia-like set of variations. Towards the end of the piece, the same agitated musical idea from the first movement is interpolated. Compared to the previous four sonatas, this work is more compliant with the tradition of the piano sonata. Duration: approximately 20 minutes.