Increasing ozone concentrations are observed overJapan from year to year. One cause of high ozoneconcentration in the Kanto region, which includesareas inland from large coastal cities such as metropolitanTokyo, is the transportation of precursors bysea breezes. However, high ozone concentrationsare also observed in the morning, before sea breezesapproach inland areas. In this point, there would bea possibility of residual ozone existing above thenocturnal boundary layer affects the ozone concentrationin the following morning. In this study, weutilized the Weather Research and Forecasting modeland the Community Multiscale Air Quality model toevaluate the effect of regional precursors and residualozone on ozone concentrations over the inlandKanto region. The results show that precursors emittedfrom non-metropolitan areas affected inlandozone concentrations more than did precursors frommetropolitan areas. Moreover, calculated resultsindicate downward transportation of residual ozone,resulting in increased concentration. The residualozone was also affected by precursors emitted fromnon-metropolitan areas.