diff --git a/includes/class-wc-gateway-komoju-ipn-handler.php b/includes/class-wc-gateway-komoju-ipn-handler.php
index 1fa256f..c9a2b5a 100644
--- a/includes/class-wc-gateway-komoju-ipn-handler.php
+++ b/includes/class-wc-gateway-komoju-ipn-handler.php
@@ -121,6 +121,7 @@ public function valid_response($webhookEvent)
 
         $order = $this->get_komoju_order($webhookEvent, $this->invoice_prefix);
         if ($order) {
+            $this->save_komoju_meta_data($order, $webhookEvent);
             switch ($webhookEvent->status()) {
                 case 'captured':
                     $this->payment_status_captured($order, $webhookEvent);
@@ -214,8 +215,6 @@ protected function payment_status_captured($order, $webhookEvent)
             $this->validate_amount($order, $webhookEvent->grand_total() - $webhookEvent->payment_method_fee());
         }
 
-        $this->save_komoju_meta_data($order, $webhookEvent);
-
         if ('captured' === $webhookEvent->status()) {
             $this->payment_complete($order, !empty($webhookEvent->uuid()) ? wc_clean($webhookEvent->uuid()) : '', __('IPN payment captured', 'komoju-woocommerce'));
 
diff --git a/includes/class-wc-gateway-komoju-single-slug.php b/includes/class-wc-gateway-komoju-single-slug.php
index c5c45ae..0950919 100644
--- a/includes/class-wc-gateway-komoju-single-slug.php
+++ b/includes/class-wc-gateway-komoju-single-slug.php
@@ -205,6 +205,17 @@ public function process_payment($order_id, $payment_type = null)
         // Otherwise we will redirect to the KOMOJU hosted page.
         $token = sanitize_text_field($_POST['komoju_payment_token']);
 
+        // Gimmick: If there is a KOMOJU payment UUID already set for the order, try to cancel the preceding payment.
+        // Some considerations:
+        // - It will be helpful to prevent duplicated Konbini payments, which can be caused through the "order-pay" page.
+        // - If the metadata is set, the payment already exists, and it is safe to cancel the payment.
+        //   - It is also worth to note that the paths to this code guarantee that this order is payable, i.e., no payment is captured or has expired yet, and therefore it is cancellable.
+        // - If the metadata is not set, there is nothing we can do anyway.
+        $komoju_payment_id = $order->get_meta('komoju_payment_id');
+        if (!empty($komoju_payment_id)) {
+            $this->komoju_api->cancel($komoju_payment_id, []);
+        }
+
         if (!$token || $token === '') {
             return parent::process_payment($order_id, $this->payment_method['type_slug']);
         }
@@ -215,6 +226,9 @@ public function process_payment($order_id, $payment_type = null)
             'payment_details' => $token,
         ]);
 
+        $order->set_transaction_id($session->payment_data->external_order_num);
+        $order->save();
+
         if ($result->redirect_url) {
             return [
                 'result'   => 'success',
diff --git a/komoju-php/komoju-php/lib/komoju/KomojuApi.php b/komoju-php/komoju-php/lib/komoju/KomojuApi.php
index 46bea67..a31ea42 100644
--- a/komoju-php/komoju-php/lib/komoju/KomojuApi.php
+++ b/komoju-php/komoju-php/lib/komoju/KomojuApi.php
@@ -59,6 +59,11 @@ public function refund($paymentUuid, $payload)
         return $this->post('/api/v1/payments/' . $paymentUuid . '/refund', $payload);
     }
 
+    public function cancel($paymentUuid, $payload)
+    {
+        return $this->post('/api/v1/payments/' . $paymentUuid . '/cancel', $payload);
+    }
+
     private function get($uri, $asArray = false)
     {
         $ch = curl_init($this->endpoint . $uri);