The present application relates primarily to a transfer device (1) for delivering a medical fluid to a medical fluid container (3), the transfer device (1) comprising at least- a cannula (4) with a blunt tip (5) formed at a distal end (6) of the cannula (4) and with a side opening (7) arranged at an axial distance (8) from the blunt tip (5) and- a retractable sheath (9), the sheath (9) being configured to repeatedly expose and seal the side opening (7),wherein the distal end section of the sheath (9) has an open front surface (10) for passing through at least a part of the cannula (4).The present application further relates to a transfer system comprising said transfer device and a bung for sealing a medical fluid container.