Dr. Mustafa Mutahari is a Researcher at Toyohashi University of Technology (TUT), Japan, where his work focuses on urban and transportation systems, digital accessibility, and sustainable urban planning. He holds a PhD in Engineering, specializing in Architecture and Civil Engineering with a focus on urban and transportation systems. His research develops multi-layer network urban simulation models that integrate physical accessibility, digital service substitution, and social network dynamics to evaluate land use–transport interaction and smart city policy scenarios. His recent publications in MDPI Sustainability examine the factors driving digital service substitution and its implications for residential relocation and quality of life, drawing on large-scale nationwide survey data from Japan. He collaborates closely with Professor Nao Sugiki and colleagues at Gifu University on extensions of the Social Dynamics Simulation (SDS) framework, and has presented this work at international venues including the World Conference on Transport Research. His current research examines how rising digital accessibility reshapes urban population distribution, transportation demand, and compact-city policy objectives.