A radio terminal (3) can perform carrier aggregation using a first cell (10) of a first radio station (1) and a second cell (20) of a second radio station (2). The first radio station (1) performs, with the radio terminal (3), radio resource control for the first cell (10) and the second cell (20) in order to perform the carrier aggregation. Further, the first radio station (1) transmits, to the second radio station (2), update information regarding an update to a configuration related to the radio resource control for the second cell (20). It is thus, for example, possible to prevent or reduce data transmission/reception failures which would otherwise occur while a configuration of radio parameters or the like is being changed by a radio terminal in carrier aggregation of a plurality of cells served by different radio stations.