diff --git a/src/main/java/icu/samnyan/aqua/sega/general/service/CardService.kt b/src/main/java/icu/samnyan/aqua/sega/general/service/CardService.kt
index f377871e..16b6a9fa 100644
--- a/src/main/java/icu/samnyan/aqua/sega/general/service/CardService.kt
+++ b/src/main/java/icu/samnyan/aqua/sega/general/service/CardService.kt
@@ -6,6 +6,7 @@ import org.springframework.stereotype.Service
 import java.time.LocalDateTime
 import java.util.*
 import java.util.concurrent.ThreadLocalRandom
+import kotlin.jvm.optionals.getOrNull
 
 /**
  * @author samnyan (privateamusement@protonmail.com)
@@ -46,6 +47,38 @@ class CardService(val cardRepo: CardRepository) {
         accessTime = registerTime
     })
 
+    /**
+     * Try to look up a card by a string ID. This ID could be one of the following:
+     *
+     * 1. An AIME access code (as a string stored directly in `luid` field)
+     * 2. A Felica IDm (as a hex string 01:2E:XX:XX:XX:XX:XX:XX), converted to int64 and stored in `luid` field
+     * 3. An NFC Serial (as a hex string XX:XX:XX:XX), converted to Felica by masking it with 01:2E:FF:FF:FF:FF:FF:FF
+     * 4. Any of (2) or (3) converted to a decimal string, which is honestly the same as (1) so ignore this case
+     */
+    fun tryLookup(id: String): Card? {
+        // Check case (1) and (4)
+        cardRepo.findByLuid(id)?.getOrNull()?.let { return it }
+        cardRepo.findByLuid(id.padStart(20, '0'))?.getOrNull()?.let { return it }
+
+        // Check case (2)
+        // First remove the colons
+        val idm = id.replace(":", "")
+        // Then convert to long, left pad zeros to make 20 digits, and look up
+        idm.toLongOrNull(16)?.let { idmLong ->
+            cardRepo.findByLuid("%020d".format(idmLong))?.getOrNull()?.let { return it }
+        }
+
+        // Check case (3)
+        idm.padStart(16, '0').takeLast(12).let { "012E$it" }.let { idmMasked ->
+            idmMasked.toLongOrNull(16)?.let { idmMaskedLong ->
+                cardRepo.findByLuid("%020d".format(idmMaskedLong))?.getOrNull()?.let { return it }
+            }
+        }
+
+        // If nothing is found, return null
+        return null
+    }
+
     fun randExtID(lower: Long = 0, upper: Long = 99999999): Long {
         var eid = ThreadLocalRandom.current().nextLong(lower, upper)
         while (cardRepo.findByExtId(eid).isPresent) {