A printing-fluid cartridge (30, 230, 330, 430, 530) configured to be inserted into a printing-fluid consuming apparatus in an insertion direction crossing a gravitational direction and attached to the printing-fluid consuming apparatus in an upright posture, the printing-fluid cartridge (30, 230, 330, 430, 530) comprising: a front surface (40, 49, 340, 349, 440, 540) facing frontward in a frontward direction in the upright posture of the printing-fluid cartridge (30, 230, 330, 430, 530); a rear surface (41, 341, 441, 541) spaced away from the front surface (40, 49, 340, 349, 440, 540) in a rearward direction crossing the gravitational direction in the upright posture, the rearward direction being opposite the frontward direction, the rear surface (41, 341, 441, 541) facing rearward in the upright posture, the printing-fluid cartridge (30, 230, 330, 430, 530) defining a rearmost point in the frontward direction; a storage chamber (32, 33, 432, 532) configured to store printing fluid therein, the storage chamber (32, 33, 432, 532) being disposed between the front surface (40, 49, 340, 349, 440, 540) and the rear surface (41, 341, 441, 541) in the frontward direction in the upright posture; a supply portion (34, 434 534) provided at the front surface (40, 49, 340, 349, 440, 540), the supply portion (34, 434, 534) having a supply port (71, 76, 471, 571) through which the printing fluid is configured to flow out of the storage chamber (32, 33, 432, 532) in the frontward direction in the upright posture, wherein the printing-fluid cartridge (30, 230, 330, 430, 530) inserted in the printing-fluid consuming apparatus is pivotable about the supply port (71, 76, 471, 571); an upper surface (39, 339,439, 539) extending between the front surface (40, 49, 340, 349, 440, 540) and the rear surface (41, 341, 441, 541), the upper surface (39, 339, 439, 539) being positioned upward relative to the storage chamber (32, 33, 432, 532) and facing upward in the upright posture; an electrical interface (64, 464, 564) disposed at the upper surface (39, 339,439, 539) and facing upward in the upright posture; and a locking surface (151, 451) disposed at the upper surface (39, 339,439, 539) and facing rearward in the upright posture; wherein: the electrical interface (64, 464, 564) is positioned closer to the supply port (71, 76, 471, 571) than the locking surface (151, 451) is to the supply port (71, 76, 471, 571) in the frontward direction; and the locking surface (151, 451) is positioned closer to the rearmost point than to the electrical interface (64, 464, 564) in the frontward direction; characterized in that: the locking surface (151, 451) and the electrical interface (64, 464, 564) are positioned rearward relative to the supply port (71, 76, 471, 571) of the supply portion (34, 434, 534). a front surface (40, 49, 340, 349, 440, 540) facing frontward in a frontward direction in the upright posture of the printing-fluid cartridge (30, 230, 330, 430, 530); a rear surface (41, 341, 441, 541) spaced away from the front surface (40, 49, 340, 349, 440, 540) in a rearward direction crossing the gravitational direction in the upright posture, the rearward direction being opposite the frontward direction, the rear surface (41, 341, 441, 541) facing rearward in the upright posture, the printing-fluid cartridge (30, 230, 330, 430, 530) defining a rearmost point in the frontward direction; a storage chamber (32, 33, 432, 532) configured to store printing fluid therein, the storage chamber (32, 33, 432, 532) being disposed between the front surface (40, 49, 340, 349, 440, 540) and the rear surface (41, 341, 441, 541) in the frontward direction in the upright posture; a supply portion (34, 434 534) provided at the front surface (40, 49, 340, 349, 440, 540), the supply portion (34, 434, 534) having a supply port (71, 76, 471, 571) through which the printing fluid is configured to flow out of the storage chamber (32, 33, 432, 532) in the frontward direction in the upright posture, wherein the printing-fluid cartridge (30, 230, 330, 430, 530) inserted in the printing-fluid consuming apparatus is pivotable about the supply port (71, 76, 471, 571); an upper surface (39, 339,439, 539) extending between the front surface (40, 49, 340, 349, 440, 540) and the rear surface (41, 341, 441, 541), the upper surface (39, 339, 439, 539) being positioned upward relative to the storage chamber (32, 33, 432, 532) and facing upward in the upright posture; an electrical interface (64, 464, 564) disposed at the upper surface (39, 339,439, 539) and facing upward in the upright posture; and a locking surface (151, 451) disposed at the upper surface (39, 339,439, 539) and facing rearward in the upright posture; wherein: the electrical interface (64, 464, 564) is positioned closer to the supply port (71, 76, 471, 571) than the locking surface (151, 451) is to the supply port (71, 76, 471, 571) in the frontward direction; and the locking surface (151, 451) is positioned closer to the rearmost point than to the electrical interface (64, 464, 564) in the frontward direction; characterized in that: the locking surface (151, 451) and the electrical interface (64, 464, 564) are positioned rearward relative to the supply port (71, 76, 471, 571) of the supply portion (34, 434, 534). the electrical interface (64, 464, 564) is positioned closer to the supply port (71, 76, 471, 571) than the locking surface (151, 451) is to the supply port (71, 76, 471, 571) in the frontward direction; and the locking surface (151, 451) is positioned closer to the rearmost point than to the electrical interface (64, 464, 564) in the frontward direction;