A radio terminal device, comprising: a communication unit configured to perform dual connectivity using a Master Cell Group, MCG, served by a first base station device and a Secondary Cell Group, SCG, served by a second base station device; and a control unit configured to: receive, from the second base station device, Downlink Control Information, DCI, containing control information used for calculating a second transmission power in a second uplink time unit on the SCG, wherein the second uplink time unit is different from a first uplink time unit where a first transmission power is calculated for the MCG, calculate the first transmission power in the first uplink time unit on the MCG, and calculate the second transmission power in the second uplink time unit on the SCG, wherein the control unit is further configured to: calculate the second transmission power used in the second uplink time unit on the SCG based on surplus power obtained by subtracting the first transmission power in the first uplink time unit on the MCG from a maximum uplink transmission power for the radio terminal device in a section in which the first uplink time unit and the second uplink time unit, which is different from the first uplink time unit, overlap, transmit, to the first base station device via the communication unit, an uplink transmission based on the calculated first transmission power in the first uplink time unit on the MCG, and transmit, to the second base station device via the communication unit, an uplink transmission based on the calculated second transmission power on the SCG in the section in which the first uplink time unit and the second uplink time unit, which is different from the first uplink time unit, overlap. a communication unit configured to perform dual connectivity using a Master Cell Group, MCG, served by a first base station device and a Secondary Cell Group, SCG, served by a second base station device; and a control unit configured to: receive, from the second base station device, Downlink Control Information, DCI, containing control information used for calculating a second transmission power in a second uplink time unit on the SCG, wherein the second uplink time unit is different from a first uplink time unit where a first transmission power is calculated for the MCG, calculate the first transmission power in the first uplink time unit on the MCG, and calculate the second transmission power in the second uplink time unit on the SCG, receive, from the second base station device, Downlink Control Information, DCI, containing control information used for calculating a second transmission power in a second uplink time unit on the SCG, wherein the second uplink time unit is different from a first uplink time unit where a first transmission power is calculated for the MCG, calculate the first transmission power in the first uplink time unit on the MCG, and calculate the second transmission power in the second uplink time unit on the SCG, wherein the control unit is further configured to: calculate the second transmission power used in the second uplink time unit on the SCG based on surplus power obtained by subtracting the first transmission power in the first uplink time unit on the MCG from a maximum uplink transmission power for the radio terminal device in a section in which the first uplink time unit and the second uplink time unit, which is different from the first uplink time unit, overlap, transmit, to the first base station device via the communication unit, an uplink transmission based on the calculated first transmission power in the first uplink time unit on the MCG, and transmit, to the second base station device via the communication unit, an uplink transmission based on the calculated second transmission power on the SCG in the section in which the first uplink time unit and the second uplink time unit, which is different from the first uplink time unit, overlap. calculate the second transmission power used in the second uplink time unit on the SCG based on surplus power obtained by subtracting the first transmission power in the first uplink time unit on the MCG from a maximum uplink transmission power for the radio terminal device in a section in which the first uplink time unit and the second uplink time unit, which is different from the first uplink time unit, overlap, transmit, to the first base station device via the communication unit, an uplink transmission based on the calculated first transmission power in the first uplink time unit on the MCG, and transmit, to the second base station device via the communication unit, an uplink transmission based on the calculated second transmission power on the SCG in the section in which the first uplink time unit and the second uplink time unit, which is different from the first uplink time unit, overlap.