Developer supply container and developer supplying system

A developer supply container comprising:

• a developer accommodating portion accommodating developer;
• a developer discharging portion in fluid communication with the developer accommodating portion, with the developer accommodating portion being rotatable about a rotational axis and relative to the developer discharging portion, and with the developer discharging portion being provided with a developer discharge opening configured to permit discharging of the developer to outside of the developer supply container;
• a hook positioned at each of opposite sides of the developer discharging portion and below a horizontal plane that includes the rotational axis when the developer supply container is oriented with the developer discharge opening positioned at a bottom side of the developer discharging portion, with each of the hooks being movable between a first position and a second position, with the hooks positioned at the second positions being closer to the horizontal plane than the hooks positioned at the first positions are to the horizontal plane, and with the hooks positioned at the second positions being closer to the developer accommodating portion in a direction of the rotational axis than the hooks positioned at the first positions are to the developer accommodating portion in the direction of the rotational axis;
• and
• a slider provided on the developer discharging portion, the slider being configured to be movable in the direction of the rotational axis toward the developer accommodating portion, and the slider being configured to transmit a force from outside of the developer supply container to the hooks so as to cause the hooks to slide from the first positions to the second positions.