Japanese Cedar is a coniferous evergreen timber tree that is found in Japan popularly known as Sugi. It is dense and evergreen which spreads branches in whorls about the trunk. But at the same time, it is dangerous as it spreads pollen i.e. allergic and many people get affected from it. Hay Fever is disease most commonly caused by pollen from Japanese Cedar. Hay Fever is a global phenomenon but in Japan, there are man-made factors at work that make it particularly severe. It is a is a reaction caused by inhaling airborne particles, such as pollen.