An ink cartridge includes a case including an ink chamber configured to store ink therein, and a particular face facing an exterior of the case and having a first opening formed therethrough. The ink cartridge also includes an ink supply portion extending from a particular portion of the particular face in a particular direction, in which the particular portion surrounds the first opening, and the ink supply portion has a tube shape. The ink supply portion includes a particular chamber formed therein, an end wall having a second opening formed therethrough, and a peripheral wall extending from the end wall. The ink supply portion is configured to supply ink from the ink chamber to the exterior of the case via the particular chamber and the second opening. Moreover, the ink cartridge includes a plurality of protrusions. Each of the plurality of protrusions extend from the peripheral wall in a corresponding radial direction with respect to the peripheral wall, and extends in an axial direction of the peripheral wall. Each corresponding radial direction is perpendicular to the axial direction of the peripheral wall, and the axial direction of the peripheral wall is parallel to the particular direction. Moreover, each adjacent pair of the plurality of protrusions defines an ink holding space therebetween, and the ink holding space has a first end and a second opposite the first end, in which the first end is positioned closer to the end wall than the second end is positioned to the end wall, and the ink holding space is open at the first end.