This session will focus on technologies and applications for visualizing electromagnetic field distribution in high-frequency bands such as millimeter wave and THz. With the recent development of high-frequency devices, it is expected that a variety of devices will be developed that apply these technologies. Visualization of high-frequency electromagnetic fields will lead to applications to verify the efficient operation of such high-frequency devices and to evaluate their characteristics for various objects. In this session, we will explore from method development such as devices and systems for visualization to various applications.