To the general public, Yoko Ono is best known as the wife of John Lennon. Some may have a vague inkling that she is important for something other than the far-out records she made with her husband, but without knowing exactly what.

Yet "Yes Yoko Ono," the current retrospective of her work on display at Art Tower Mito, emphatically proves, if Ono had never met John Lennon, if they had never consummated their romantic and artistic relationship, she would still be considered a significant artist in her own right. Spanning nearly 40 years, the exhibition never denies Ono's partnership with Lennon. At the same time, by focusing on her early work, it details the singularity of her own artistic vision and its importance to contemporary art.

Ono's "instruction paintings," which are not paintings at all but conceptual poems designed to prompt the viewer into various intellectual exercises, are an important step in the history of conceptual art. Her events, such as "Cut Piece" (1964), in which audiences members literally cut the clothes from her body, are landmarks of performance art as well as early feminism. Lennon inspired her and supported her, but he did not make her. He merely introduced her to a larger audience.