In the book The Life and Works of Haku Maki by Daniel Tretiak (Outskirts Press, Inc. Denver, CO. 2007), this work is illustrated on page 5 along with two other calligraphic prints. In the description on page 4, Tretiak notes that the calligraphy used in the image is from the Chinese "Grass writing" technique, Cao Shu, which refers to what the West calls cursive.
Much of Maki's work in his most productive years was based on "kanji," a style of Chinese calligraphy that was adapted by the Japanese as trade between the two countries became more prevalent in the 5th century AD.