Developer container and image forming system

A developer container configured to accommodate a developer, comprising:

• a pouch including a bottom portion and a side portion extending from the bottom portion to form an opening;
• a communication member configured to make inside of the pouch communicate with outside, the communication member being fixed to the opening of the pouch;
• and
• a cap formed by injection molding and configured to be detached from the communication member by rotation with respect to the communication member, a marking indicating a direction of rotation to detach the cap from the communication member and a parting line extending in a direction along a rotation axis of the cap being disposed on an outer peripheral surface of the cap, the marking including an arrowhead part formed to protrude from the outer peripheral surface, the arrowhead part including a rear end located upstream and a front end located downstream in the direction of rotation,
• wherein a direction connecting the opening and the bottom portion of the pouch is a first direction, a longitudinal direction of a cross-sectional shape of the pouch is a second direction, the second direction being orthogonal to the first direction, and a direction orthogonal to the first direction and the second direction is a third direction,
• wherein in a state of the cap attached to the communication member, the cap has a reference position in the second direction on the outer peripheral surface, the reference position being a position corresponding to where a thickness of the pouch in the third direction is maximized in a case where the pouch is viewed along the first direction, and
• wherein the rear end is disposed along the outer peripheral surface between a first position and a second position in the direction of rotation, the rear end being located to overlap the parting line, the first position of the rear end being a position 45° upstream from the reference position in the direction of rotation with the rotation axis as a center of rotation, the second position being a position 45° downstream from the reference position in the direction of rotation with the rotation axis as the center of rotation.