The Alphabetical Orgasm is a 1991 series of graphic artwork by Osamu Sato. It may be viewed in high resolution on Sato's personal site. It was published in book form the same year by Tierrart, with additional messages and doodles in between each letter. The fully scanned book is available on Sato Archives (large PDF warning).
According to the defunct OSD website, there were 2 exhibitions for The Alphabetical Orgasm: one at the Tierrart Tokyo Gallery in November '91, and another at the Takichi Studio Com in April '92 (verification of translations needed). The postcard scans shown below, showcased on the same website, seem to corroborate this information.