Dr. Masanobu Iwanaga, Lead Researcher of the Plasmonics Group, Photonic Materials Unit (Unit Director: Kazuaki Sakoda), National Institute for Materials Science (President: Sukekatsu Ushioda), carried out a theoretical analysis of light propagation for a typical fishnet metamaterial, which has attracted the strongest attention in the optical wavelengths from the visible to the near infrared, and elucidated for the first time the counter-propagating light which makes the negative refraction phenomenon possible. This achievement enables a direct, quantitative understanding of the phenomenon of negative refraction in metamaterials, which had previously been explained by an effective permittivity-permeability model. Based on the deeper understanding provided by Dr. Iwanaga's research, progress is expected in research and development using negative refraction in super-resolution imaging and super-resolution lithography. This research was carried out as a part of the research topic "Super Resolution Microscope Based on Transfer Optics and In-Vivo Observation of Mesoscopic Dynamics" (Researcher: Masanobu Iwanaga) in the Japan Science and Technology Agency's JST PRESTO Project "Innovative Use of Light and Materials/Life"(Hiroshi Masuhara, Professor at the Graduate School of Materials Science, Nara Institute of Science and Technology and Professor at the National Chiao Tung University, Taiwan).