A mobile agent is regarded as an attractive technology when developing distributed applications in mobile and ubiquitous computing environments. In this paper, we present ODDUGI, a java-based ubiquitous mobile agent system. The ODDUGI mobile agent system provides fault tolerance, security, location management and message delivery mechanisms in a multi-region mobile agent computing environment. We describe the architecture, design concepts and main features of the ODDUGI. In addition, we present the One-Touch Campus Service application developed on the basis of ODDUGI in mobile and ubiquitous computing environments.