As per your concern, we see that, you have clicked on the "confirm shipment" button for the order - ●●. However, the product to be sent is still with you. In this case, we request you to, communicate the same with the buyer and ship the product to the buyer at the earliest.
Also in case if the product to be sent by you is not available with you to be able to fulfil the order, then in that case, since you have clicked on the "confirm shipment" button so the buyer has already been charged, so in this case, you can go ahead to refund the order.
Also we are providing the below link for more insight into the "order process" and "confirm shipment" details:
オーダーを完了するのに、あなたが発送する品が利用可能でない場合は"confirm shipment" をすでに押したとのことなので、購入者にはすでに請求がなされています。なのでこの場合は注文の返金を行ってください。
オーダープロセスや発送確認について以下のリンクで説明しています。