diff --git a/src/Microsoft.Health.Fhir.CosmosDb.UnitTests/Features/Storage/CosmosFhirDataStoreTests.cs b/src/Microsoft.Health.Fhir.CosmosDb.UnitTests/Features/Storage/CosmosFhirDataStoreTests.cs
index 3c2cee7b2d..fd37b26671 100644
--- a/src/Microsoft.Health.Fhir.CosmosDb.UnitTests/Features/Storage/CosmosFhirDataStoreTests.cs
+++ b/src/Microsoft.Health.Fhir.CosmosDb.UnitTests/Features/Storage/CosmosFhirDataStoreTests.cs
@@ -10,8 +10,8 @@
 using System.Net.Http;
 using System.Reflection;
 using System.Runtime.CompilerServices;
+using System.Text;
 using System.Threading;
-using System.Threading.Tasks;
 using Hl7.Fhir.Model;
 using Hl7.Fhir.Serialization;
 using Microsoft.Azure.Cosmos;
@@ -88,6 +88,48 @@ public CosmosFhirDataStoreTests()
                 requestContextAccessor);
         }
 
+        [Fact]
+        public void GivenCanonicallyEquivalentJapaneseText_WhenComparingResourcesWithoutVersionMetadata_ThenTheDataMatches()
+        {
+            const string existingData = "{\"resourceType\":\"Patient\",\"id\":\"id1\",\"meta\":{\"versionId\":\"1\",\"lastUpdated\":\"2026-08-26T21:00:00+00:00\"},\"name\":[{\"text\":\"\u304C\"}]}";
+            const string incomingData = "{\"resourceType\":\"Patient\",\"id\":\"id1\",\"meta\":{\"versionId\":\"2\",\"lastUpdated\":\"2026-08-26T21:01:00+00:00\"},\"name\":[{\"text\":\"\u304B\u3099\"}]}";
+
+            var lastModified = new DateTimeOffset(2026, 8, 26, 21, 0, 0, TimeSpan.Zero);
+            var request = new ResourceRequest(HttpMethod.Put, "http://fhir");
+
+            var existingResource = new FhirCosmosResourceWrapper(
+                "id1",
+                "1",
+                "Patient",
+                new RawResource(existingData, FhirResourceFormat.Json, isMetaSet: true),
+                request,
+                lastModified,
+                deleted: false,
+                history: false,
+                searchIndices: null,
+                compartmentIndices: null,
+                lastModifiedClaims: null);
+
+            var incomingResource = new FhirCosmosResourceWrapper(
+                "id1",
+                "2",
+                "Patient",
+                new RawResource(incomingData, FhirResourceFormat.Json, isMetaSet: true),
+                request,
+                lastModified.AddMinutes(1),
+                deleted: false,
+                history: false,
+                searchIndices: null,
+                compartmentIndices: null,
+                lastModifiedClaims: null);
+
+            var existingResourceData = CosmosFhirDataStore.RemoveVersionIdAndLastUpdatedFromMeta(existingResource);
+            var incomingResourceData = CosmosFhirDataStore.RemoveVersionIdAndLastUpdatedFromMeta(incomingResource);
+
+            Assert.Equal(existingResourceData, incomingResourceData);
+            Assert.True(existingResourceData.IsNormalized(NormalizationForm.FormC));
+        }
+
         [Fact]
         public async Task GivenAQuery_WhenASinglePageReturnsRequestedCount_ASingleQueryIsPerformced()
         {
diff --git a/src/Microsoft.Health.Fhir.CosmosDb/Features/Storage/CosmosFhirDataStore.cs b/src/Microsoft.Health.Fhir.CosmosDb/Features/Storage/CosmosFhirDataStore.cs
index d0c2b72a0c..23a8183b77 100644
--- a/src/Microsoft.Health.Fhir.CosmosDb/Features/Storage/CosmosFhirDataStore.cs
+++ b/src/Microsoft.Health.Fhir.CosmosDb/Features/Storage/CosmosFhirDataStore.cs
@@ -12,22 +12,20 @@
 using System.Linq;
 using System.Net;
 using System.Text;
-using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 using EnsureThat;
+using Hl7.Fhir.Utility;
 using Microsoft.Azure.Cosmos;
 using Microsoft.Azure.Cosmos.Scripts;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Health.Abstractions.Exceptions;
-using Microsoft.Health.Core;
 using Microsoft.Health.Core.Features.Context;
 using Microsoft.Health.Extensions.DependencyInjection;
 using Microsoft.Health.Fhir.Core.Configs;
 using Microsoft.Health.Fhir.Core.Exceptions;
 using Microsoft.Health.Fhir.Core.Extensions;
-using Microsoft.Health.Fhir.Core.Features;
 using Microsoft.Health.Fhir.Core.Features.Conformance;
 using Microsoft.Health.Fhir.Core.Features.Context;
 using Microsoft.Health.Fhir.Core.Features.Definition;
@@ -432,10 +430,13 @@ await retryPolicy.ExecuteAsync(
                 // If not a delete then check if its an update with no data change
                 if (!cosmosWrapper.IsDeleted)
                 {
-                    // check if the new resource data is same as existing resource data
-                    if (string.Equals(RemoveVersionIdAndLastUpdatedFromMeta(existingItemResource), RemoveVersionIdAndLastUpdatedFromMeta(cosmosWrapper), StringComparison.Ordinal))
+                    string existingData = RemoveVersionIdAndLastUpdatedFromMeta(existingItemResource);
+                    string newData = RemoveVersionIdAndLastUpdatedFromMeta(cosmosWrapper);
+
+                    // Check if the new resource data is same as existing resource data
+                    if (string.Equals(existingData, newData, StringComparison.Ordinal))
                     {
-                        // Do not store the duplicate data, for a update with no impact - returning existingItemResource as no updates
+                        // Do not store the duplicate data, for a update with no impact - returning existingItemResource as no updates.
                         return new UpsertOutcome(existingItemResource, SaveOutcomeType.Updated);
                     }
                 }
@@ -876,11 +877,19 @@ private static string RemoveTrailingZerosFromMillisecondsForAGivenDate(DateTimeO
             return formattedDate.Replace(milliseconds, trimmedMilliseconds, StringComparison.Ordinal);
         }
 
-        private static string RemoveVersionIdAndLastUpdatedFromMeta(FhirCosmosResourceWrapper resourceWrapper)
+        internal static string RemoveVersionIdAndLastUpdatedFromMeta(FhirCosmosResourceWrapper resourceWrapper)
         {
             var versionToReplace = resourceWrapper.RawResource.IsMetaSet ? resourceWrapper.Version : "1";
-            var rawResource = resourceWrapper.RawResource.Data.Replace($"\"versionId\":\"{versionToReplace}\"", string.Empty, StringComparison.Ordinal);
-            return rawResource.Replace($"\"lastUpdated\":\"{RemoveTrailingZerosFromMillisecondsForAGivenDate(resourceWrapper.LastModified)}\"", string.Empty, StringComparison.Ordinal);
+            var rawResource = resourceWrapper.RawResource.Data
+                .Replace($"\"versionId\":\"{versionToReplace}\"", string.Empty, StringComparison.Ordinal)
+                .Replace($"\"lastUpdated\":\"{RemoveTrailingZerosFromMillisecondsForAGivenDate(resourceWrapper.LastModified)}\"", string.Empty, StringComparison.Ordinal);
+
+            // StringComparison.Ordinal performs a byte-by-byte comparison without any Unicode normalization. This is problematic for Japanese characters because: Japanese characters
+            // can be represented in multiple equivalent Unicode forms: NFD (Canonical Decomposition) or NFC (Canonical Composition).
+            // If a client sends Japanese text in one normalization form(e.g., NFD) but a previous version stored it in another form(e.g., NFC), the Ordinal comparison will fail even though
+            // the characters look identical.
+            // English/ASCII characters don't have normalization variants, so this only affects languages like Japanese, Korean, Vietnamese, etc.
+            return rawResource.Normalize(NormalizationForm.FormC);
         }
 
         public async Task BuildAsync(ICapabilityStatementBuilder builder, CancellationToken cancellationToken)