Yoshine Hada (Fig. 1) was likely the first Japanese scientist who could be called a "planktologist". He was not the first to study plankton in Japan. That honor probably goes to Kintaro Okamura (1867-1935) who worked on marine phytoplankton. He is said to have been the first to translate 'plankton' into Japanese in 1900 (Omori, 2002). However, Hada, unlike Okamura, worked on a large variety of planktonic taxa and in a wide range of environments. He worked on copepods, rotifers, foraminifera, heliozoans, ciliates, amoeba, and many different taxa of phytoplankton. Hada published on the plankton of freshwater and saline lakes, and on marine plankton in sites ranging from the near shore waters of Japan, to the North Pacific, the Tropical Pacific, the Indian Ocean, and Antarctica. Today he may be best, but vaguely, known to the many plankton researchers who work on harmful algal blooms as he first discovered and described two troublesome flagellates species. In 1967, Hada described now known as Heterosigma akashiwo, naming it for its ability to form red tides as akashiwo is red tide in Japanese (Hada, 1967a). The species has since been known under many different names, see Hara and Chihara (1987) for an introduction to its confusing taxonomic history. Hada described another bloom-forming species now known as Chattonella antiqua in 1974 as Hemieutreptia antiqua (Hada, 1974a). Here a brief sketch will be given of the little known career of Yoshine Hada and his remarkably diverse contributions to plankton research will be highlighted.