The Low Carbon and Waste Recycling Research Center attached to the Graduate School of Environmental, Life and Natural Sciences, Okayama University offers public lectures to the general public every June. The theme varies each year. For more information, please visit the Okayama University Open Course website. In the R4th year, Professor Hafu-Yi gave a theme of ``Recent waste research'', and in the R5th year, the theme was ``Efforts to prevent plastic dumping into rivers in Cambodia''.