diff --git a/src/Persistence/Initialization/Updates/AddCrestOfMonarchDropGroupUpdateSeason6.cs b/src/Persistence/Initialization/Updates/AddCrestOfMonarchDropGroupUpdateSeason6.cs
new file mode 100644
index 000000000..7021f2420
--- /dev/null
+++ b/src/Persistence/Initialization/Updates/AddCrestOfMonarchDropGroupUpdateSeason6.cs
@@ -0,0 +1,81 @@
+// <copyright file="AddCrestOfMonarchDropGroupUpdateSeason6.cs" company="MUnique">
+// Licensed under the MIT License. See LICENSE file in the project root for full license information.
+// </copyright>
+
+namespace MUnique.OpenMU.Persistence.Initialization.Updates;
+
+using System.Runtime.InteropServices;
+using MUnique.OpenMU.DataModel.Configuration;
+using MUnique.OpenMU.Persistence.Initialization.VersionSeasonSix.Maps;
+using MUnique.OpenMU.PlugIns;
+
+/// <summary>
+/// This update adds the Crest of Monarch drop item group for the Icarus map.
+/// </summary>
+[PlugIn]
+[Display(Name = PlugInName, Description = PlugInDescription)]
+[Guid("FF14A478-3EA8-4C41-A298-8E6698D5973D")]
+public class AddCrestOfMonarchDropGroupUpdateSeason6 : UpdatePlugInBase
+{
+    /// <summary>
+    /// The plug in name.
+    /// </summary>
+    internal const string PlugInName = "Add Crest of Monarch Drop Group";
+
+    /// <summary>
+    /// The plug in description.
+    /// </summary>
+    internal const string PlugInDescription = "Adds the Crest of Monarch (Loch's Feather +1) drop item group to Icarus.";
+
+    /// <inheritdoc />
+    public override UpdateVersion Version => UpdateVersion.AddCrestOfMonarchDropGroupSeason6;
+
+    /// <inheritdoc />
+    public override string DataInitializationKey => VersionSeasonSix.DataInitialization.Id;
+
+    /// <inheritdoc />
+    public override string Name => PlugInName;
+
+    /// <inheritdoc />
+    public override string Description => PlugInDescription;
+
+    /// <inheritdoc />
+    public override bool IsMandatory => true;
+
+    /// <inheritdoc />
+    public override DateTime CreatedAt => new(2026, 03, 13, 12, 0, 0, DateTimeKind.Utc);
+
+    /// <inheritdoc />
+#pragma warning disable CS1998
+    protected override async ValueTask ApplyAsync(IContext context, GameConfiguration gameConfiguration)
+#pragma warning restore CS1998
+    {
+        var map = gameConfiguration.Maps.First(m => m.Number == Icarus.Number && m.Discriminator == 0);
+        var lochsFeather = gameConfiguration.Items.First(item => item.Group == 13 && item.Number == 14);
+        var crestId = GuidHelper.CreateGuid<DropItemGroup>(Icarus.Number, 2);
+
+        var crestGroup = gameConfiguration.DropItemGroups.FirstOrDefault(group => group.GetId() == crestId);
+        if (crestGroup is null)
+        {
+            crestGroup = context.CreateNew<DropItemGroup>();
+            crestGroup.SetGuid(Icarus.Number, 2);
+            gameConfiguration.DropItemGroups.Add(crestGroup);
+        }
+
+        crestGroup.Description = "Crest of Monarch";
+        crestGroup.Chance = 0.001;
+        crestGroup.MinimumMonsterLevel = 82;
+        crestGroup.MaximumMonsterLevel = null;
+        crestGroup.ItemLevel = 1;
+        if (crestGroup.PossibleItems.Count != 1 || crestGroup.PossibleItems.First().GetItemId() != lochsFeather.GetItemId())
+        {
+            crestGroup.PossibleItems.Clear();
+            crestGroup.PossibleItems.Add(lochsFeather);
+        }
+
+        if (!map.DropItemGroups.Any(group => group.GetId() == crestGroup.GetId()))
+        {
+            map.DropItemGroups.Add(crestGroup);
+        }
+    }
+}
diff --git a/src/Persistence/Initialization/Updates/UpdateVersion.cs b/src/Persistence/Initialization/Updates/UpdateVersion.cs
index 77180a772..3af0fbb00 100644
--- a/src/Persistence/Initialization/Updates/UpdateVersion.cs
+++ b/src/Persistence/Initialization/Updates/UpdateVersion.cs
@@ -359,8 +359,12 @@ public enum UpdateVersion
     /// </summary>
     RemoveJewelDropLevelGapSeason6 = 70,
 
-    /// <summary>
     /// The version of the <see cref="FixRageFighterMultipleHitSkillsPlugIn"/>.
     /// </summary>
     FixRageFighterMultipleHitSkills = 71,
-}
\ No newline at end of file
+
+    /// <summary>
+    /// The version of the <see cref="AddCrestOfMonarchDropGroupUpdateSeason6"/>.
+    /// </summary>
+    AddCrestOfMonarchDropGroupSeason6 = 72,
+}
diff --git a/src/Persistence/Initialization/VersionSeasonSix/Maps/Icarus.cs b/src/Persistence/Initialization/VersionSeasonSix/Maps/Icarus.cs
index 607b1e842..9995c8f7b 100644
--- a/src/Persistence/Initialization/VersionSeasonSix/Maps/Icarus.cs
+++ b/src/Persistence/Initialization/VersionSeasonSix/Maps/Icarus.cs
@@ -25,13 +25,25 @@ public Icarus(IContext context, GameConfiguration gameConfiguration)
     protected override void InitializeDropItemGroups()
     {
         base.InitializeDropItemGroups();
+        var lochsFeather = this.GameConfiguration.Items.First(item => item.Group == 13 && item.Number == 14);
+
         var feather = this.Context.CreateNew<DropItemGroup>();
         feather.SetGuid(this.MapNumber, 1);
         feather.Chance = 0.001;
         feather.Description = "Loch's Feather";
         feather.MinimumMonsterLevel = 82;
-        feather.PossibleItems.Add(this.GameConfiguration.Items.First(item => item.Group == 13 && item.Number == 14));
+        feather.PossibleItems.Add(lochsFeather);
         this.MapDefinition!.DropItemGroups.Add(feather);
         this.GameConfiguration.DropItemGroups.Add(feather);
+
+        var crest = this.Context.CreateNew<DropItemGroup>();
+        crest.SetGuid(this.MapNumber, 2);
+        crest.Chance = 0.001;
+        crest.Description = "Crest of Monarch";
+        crest.MinimumMonsterLevel = 82;
+        crest.ItemLevel = 1;
+        crest.PossibleItems.Add(lochsFeather);
+        this.MapDefinition.DropItemGroups.Add(crest);
+        this.GameConfiguration.DropItemGroups.Add(crest);
     }
-}
\ No newline at end of file
+}
diff --git a/tests/MUnique.OpenMU.Persistence.Initialization.Tests/TestInitializationWithEfCore.cs b/tests/MUnique.OpenMU.Persistence.Initialization.Tests/TestInitializationWithEfCore.cs
index 383982414..b053d2a1d 100644
--- a/tests/MUnique.OpenMU.Persistence.Initialization.Tests/TestInitializationWithEfCore.cs
+++ b/tests/MUnique.OpenMU.Persistence.Initialization.Tests/TestInitializationWithEfCore.cs
@@ -5,10 +5,13 @@
 namespace MUnique.OpenMU.Persistence.Initialization.Tests;
 
 using Microsoft.Extensions.Logging.Abstractions;
+using MUnique.OpenMU.AttributeSystem;
 using MUnique.OpenMU.DataModel;
 using MUnique.OpenMU.DataModel.Configuration;
 using MUnique.OpenMU.GameLogic;
 using MUnique.OpenMU.Persistence.EntityFramework;
+using MUnique.OpenMU.Persistence.Initialization.Updates;
+using MUnique.OpenMU.Persistence.Initialization.VersionSeasonSix.Maps;
 using MUnique.OpenMU.Persistence.InMemory;
 
 /// <summary>
@@ -47,9 +50,47 @@ public async Task TestSeason6DataAsync()
         var contextProvider = new InMemoryPersistenceContextProvider();
         var dataInitialization = new VersionSeasonSix.DataInitialization(contextProvider, new NullLoggerFactory());
         await dataInitialization.CreateInitialDataAsync(1, true).ConfigureAwait(false);
+        await this.AssertIcarusFeatherAndCrestDropGroupsAsync(contextProvider).ConfigureAwait(false);
         await this.TestIfItemsFitIntoInventoriesAsync(contextProvider).ConfigureAwait(false);
     }
 
+    /// <summary>
+    /// Tests that applying the update for Crest of Monarch in Season 6 is idempotent.
+    /// </summary>
+    [Test]
+    public async Task TestSeason6CrestOfMonarchUpdatePlugInAsync()
+    {
+        var contextProvider = new InMemoryPersistenceContextProvider();
+        var dataInitialization = new VersionSeasonSix.DataInitialization(contextProvider, new NullLoggerFactory());
+        await dataInitialization.CreateInitialDataAsync(1, true).ConfigureAwait(false);
+
+        using var context = contextProvider.CreateNewContext();
+        var gameConfiguration = (await context.GetAsync<GameConfiguration>().ConfigureAwait(false)).First();
+        var map = gameConfiguration.Maps.First(m => m.Number == Icarus.Number && m.Discriminator == 0);
+
+        var crestGroupId = GuidHelper.CreateGuid<DropItemGroup>(Icarus.Number, 2);
+        if (gameConfiguration.DropItemGroups.FirstOrDefault(group => group.GetId() == crestGroupId) is { } existingCrestGroup)
+        {
+            map.DropItemGroups.Remove(existingCrestGroup);
+            gameConfiguration.DropItemGroups.Remove(existingCrestGroup);
+        }
+
+        var update = new AddCrestOfMonarchDropGroupUpdateSeason6();
+        await update.ApplyUpdateAsync(context, gameConfiguration).ConfigureAwait(false);
+        await update.ApplyUpdateAsync(context, gameConfiguration).ConfigureAwait(false);
+
+        var groups = gameConfiguration.DropItemGroups.Where(group => group.GetId() == crestGroupId).ToList();
+        Assert.That(groups, Has.Count.EqualTo(1));
+        Assert.That(map.DropItemGroups.Count(group => group.GetId() == crestGroupId), Is.EqualTo(1));
+        Assert.That(groups[0].Description.ToString(), Is.EqualTo("Crest of Monarch"));
+        Assert.That(groups[0].Chance, Is.EqualTo(0.001));
+        Assert.That(groups[0].MinimumMonsterLevel, Is.EqualTo((byte)82));
+        Assert.That(groups[0].ItemLevel, Is.EqualTo((byte)1));
+        Assert.That(groups[0].PossibleItems, Has.Count.EqualTo(1));
+        Assert.That(groups[0].PossibleItems.Single().Group, Is.EqualTo((byte)13));
+        Assert.That(groups[0].PossibleItems.Single().Number, Is.EqualTo((short)14));
+    }
+
     /// <summary>
     /// Tests the data initialization using the in-memory persistence.
     /// </summary>
@@ -114,4 +155,35 @@ private async Task TestIfItemsFitIntoInventoriesAsync(IPersistenceContextProvide
             }
         }
     }
-}
\ No newline at end of file
+
+    private async Task AssertIcarusFeatherAndCrestDropGroupsAsync(IPersistenceContextProvider contextProvider)
+    {
+        using var context = contextProvider.CreateNewConfigurationContext();
+        var gameConfiguration = (await context.GetAsync<GameConfiguration>().ConfigureAwait(false)).First();
+        var map = gameConfiguration.Maps.First(m => m.Number == Icarus.Number && m.Discriminator == 0);
+
+        var lochsFeatherGroupId = GuidHelper.CreateGuid<DropItemGroup>(Icarus.Number, 1);
+        var crestGroupId = GuidHelper.CreateGuid<DropItemGroup>(Icarus.Number, 2);
+        var featherGroup = gameConfiguration.DropItemGroups.Single(group => group.GetId() == lochsFeatherGroupId);
+        var crestGroup = gameConfiguration.DropItemGroups.Single(group => group.GetId() == crestGroupId);
+
+        Assert.That(map.DropItemGroups.Any(group => group.GetId() == lochsFeatherGroupId), Is.True);
+        Assert.That(map.DropItemGroups.Any(group => group.GetId() == crestGroupId), Is.True);
+
+        Assert.That(featherGroup.Description.ToString(), Is.EqualTo("Loch's Feather"));
+        Assert.That(featherGroup.Chance, Is.EqualTo(0.001));
+        Assert.That(featherGroup.MinimumMonsterLevel, Is.EqualTo((byte)82));
+        Assert.That(featherGroup.ItemLevel, Is.Null);
+        Assert.That(featherGroup.PossibleItems, Has.Count.EqualTo(1));
+        Assert.That(featherGroup.PossibleItems.Single().Group, Is.EqualTo((byte)13));
+        Assert.That(featherGroup.PossibleItems.Single().Number, Is.EqualTo((short)14));
+
+        Assert.That(crestGroup.Description.ToString(), Is.EqualTo("Crest of Monarch"));
+        Assert.That(crestGroup.Chance, Is.EqualTo(0.001));
+        Assert.That(crestGroup.MinimumMonsterLevel, Is.EqualTo((byte)82));
+        Assert.That(crestGroup.ItemLevel, Is.EqualTo((byte)1));
+        Assert.That(crestGroup.PossibleItems, Has.Count.EqualTo(1));
+        Assert.That(crestGroup.PossibleItems.Single().Group, Is.EqualTo((byte)13));
+        Assert.That(crestGroup.PossibleItems.Single().Number, Is.EqualTo((short)14));
+    }
+}