A first base station (1) that operates a first cell (10) is configured to receive, from a mobile station (4) through a signaling radio bearer in the first cell (10), a signal containing a NAS message that causes a setup of a data bearer in a data transfer apparatus (7) within a core network (5). The first base station (1) is also configured to forward the NAS message from the mobile station (4) to a mobility management apparatus (6) within the core network (5) and transmit, to the mobility management apparatus (6), base station information indicating a selected base station that has been selected from at least one second base station (2) and terminates a data bearer for the mobile station (4). It is thus, for example, possible to contribute to a simple establishment of a U-Plane bearer in a dual-connectivity scenario.