JMA/MRI-CPS3 will employ higher resolution atmosphere, land, ocean, and sea-ice models, compared with current operational JMA/MRI-CPS2. Eddy-permitting resolution of the new ocean model is expected to reduce the equatorial Pacific cold tongue bias. The ocean initial condition will be improved by updating from 3DVar to 4DVar DA system, and the sea-ice initial condition will be also improved by introducing sea-ice assimilation system, which is not applied in JMA/MRI-CPS2. We will also consider a weakly-coupled DA system to reduce the initialization shock. We will show preliminary results including prediction skill of annual variability and bias.