diff --git a/src/UniTask.NetCore/Linq/SkipLast.cs b/src/UniTask.NetCore/Linq/SkipLast.cs
index 5f79cf2..665e15d 100644
--- a/src/UniTask.NetCore/Linq/SkipLast.cs
+++ b/src/UniTask.NetCore/Linq/SkipLast.cs
@@ -1,775 +1,153 @@
-namespace Cysharp.Threading.Tasks.Linq
+using Cysharp.Threading.Tasks.Internal;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+
+namespace Cysharp.Threading.Tasks.Linq
 {
-    internal sealed class SkipLast
+    public static partial class UniTaskAsyncEnumerable
     {
+        public static IUniTaskAsyncEnumerable<TSource> SkipLast<TSource>(this IUniTaskAsyncEnumerable<TSource> source, Int32 count)
+        {
+            Error.ThrowArgumentNullException(source, nameof(source));
+
+            // non skip.
+            if (count <= 0)
+            {
+                return source;
+            }
+
+            return new SkipLast<TSource>(source, count);
+        }
     }
 
-
-}
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+    internal sealed class SkipLast<TSource> : IUniTaskAsyncEnumerable<TSource>
+    {
+        readonly IUniTaskAsyncEnumerable<TSource> source;
+        readonly int count;
+
+        public SkipLast(IUniTaskAsyncEnumerable<TSource> source, int count)
+        {
+            this.source = source;
+            this.count = count;
+        }
+
+        public IUniTaskAsyncEnumerator<TSource> GetAsyncEnumerator(CancellationToken cancellationToken = default)
+        {
+            return new Enumerator(source, count, cancellationToken);
+        }
+
+        sealed class Enumerator : MoveNextSource, IUniTaskAsyncEnumerator<TSource>
+        {
+            static readonly Action<object> MoveNextCoreDelegate = MoveNextCore;
+
+            readonly IUniTaskAsyncEnumerable<TSource> source;
+            readonly int count;
+            CancellationToken cancellationToken;
+
+            IUniTaskAsyncEnumerator<TSource> enumerator;
+            UniTask<bool>.Awaiter awaiter;
+            Queue<TSource> queue;
+
+            bool continueNext;
+
+            public Enumerator(IUniTaskAsyncEnumerable<TSource> source, int count, CancellationToken cancellationToken)
+            {
+                this.source = source;
+                this.count = count;
+                this.cancellationToken = cancellationToken;
+            }
+
+            public TSource Current { get; private set; }
+
+            public UniTask<bool> MoveNextAsync()
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+
+                if (enumerator == null)
+                {
+                    enumerator = source.GetAsyncEnumerator(cancellationToken);
+                    queue = new Queue<TSource>();
+                }
+
+                completionSource.Reset();
+                SourceMoveNext();
+                return new UniTask<bool>(this, completionSource.Version);
+            }
+
+            void SourceMoveNext()
+            {
+                try
+                {
+
+                    LOOP:
+                    awaiter = enumerator.MoveNextAsync().GetAwaiter();
+                    if (awaiter.IsCompleted)
+                    {
+                        continueNext = true;
+                        MoveNextCore(this);
+                        if (continueNext)
+                        {
+                            continueNext = false;
+                            goto LOOP; // avoid recursive
+                        }
+                    }
+                    else
+                    {
+                        awaiter.SourceOnCompleted(MoveNextCoreDelegate, this);
+                    }
+                }
+                catch (Exception ex)
+                {
+                    completionSource.TrySetException(ex);
+                }
+            }
+
+
+            static void MoveNextCore(object state)
+            {
+                var self = (Enumerator)state;
+
+                if (self.TryGetResult(self.awaiter, out var result))
+                {
+                    if (result)
+                    {
+                        if (self.queue.Count == self.count)
+                        {
+                            self.continueNext = false;
+
+                            var deq = self.queue.Dequeue();
+                            self.Current = deq;
+                            self.queue.Enqueue(self.enumerator.Current);
+
+                            self.completionSource.TrySetResult(true);
+                        }
+                        else
+                        {
+                            self.queue.Enqueue(self.enumerator.Current);
+
+                            if (!self.continueNext)
+                            {
+                                self.SourceMoveNext();
+                            }
+                        }
+                    }
+                    else
+                    {
+                        self.continueNext = false;
+                        self.completionSource.TrySetResult(false);
+                    }
+                }
+            }
+
+            public UniTask DisposeAsync()
+            {
+                if (enumerator != null)
+                {
+                    return enumerator.DisposeAsync();
+                }
+                return default;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/UniTask.NetCore/Linq/_FileMaker.cs b/src/UniTask.NetCore/Linq/_FileMaker.cs
index 11e8d7a..7fca4f5 100644
--- a/src/UniTask.NetCore/Linq/_FileMaker.cs
+++ b/src/UniTask.NetCore/Linq/_FileMaker.cs
@@ -307,12 +307,6 @@ namespace ___Dummy
 
 
 
-
-        public static IUniTaskAsyncEnumerable<TSource> SkipLast<TSource>(this IUniTaskAsyncEnumerable<TSource> source, Int32 count)
-        {
-            throw new NotImplementedException();
-        }
-
         
 
         public static IUniTaskAsyncEnumerable<TSource> TakeLast<TSource>(this IUniTaskAsyncEnumerable<TSource> source, Int32 count)
diff --git a/src/UniTask.NetCoreSandbox/Program.cs b/src/UniTask.NetCoreSandbox/Program.cs
index 024c8da..dc26574 100644
--- a/src/UniTask.NetCoreSandbox/Program.cs
+++ b/src/UniTask.NetCoreSandbox/Program.cs
@@ -39,9 +39,11 @@ namespace NetCoreSandbox
 
         static async Task Main(string[] args)
         {
-            await foreach (var item in UniTaskAsyncEnumerable.Range(1, 10).Do(x => Console.WriteLine("DO:" + x))
-                //.TakeWhileAwait(x => UniTask.FromResult(x < 5))
-                .Take(5)
+            await foreach (var item in UniTaskAsyncEnumerable.Range(1, 10)
+                .SelectAwait(x => UniTask.Run(() => x))
+                .SkipLast(6)
+
+
 
                 )
             {
@@ -53,6 +55,8 @@ namespace NetCoreSandbox
 
 
 
+
+
         }
 
 
diff --git a/src/UniTask.NetCoreTests/Linq/Paging.cs b/src/UniTask.NetCoreTests/Linq/Paging.cs
index d0e2b55..aef0600 100644
--- a/src/UniTask.NetCoreTests/Linq/Paging.cs
+++ b/src/UniTask.NetCoreTests/Linq/Paging.cs
@@ -39,6 +39,31 @@ namespace NetCoreTests.Linq
                 await Assert.ThrowsAsync<UniTaskTestException>(async () => await xs);
             }
         }
+        [Theory]
+        [InlineData(0, 0)]
+        [InlineData(0, 1)]
+        [InlineData(9, 0)]
+        [InlineData(9, 1)]
+        [InlineData(9, 5)]
+        [InlineData(9, 9)]
+        [InlineData(9, 15)]
+        public async Task SkipLast(int collection, int skipCount)
+        {
+            var xs = await UniTaskAsyncEnumerable.Range(1, collection).SkipLast(skipCount).ToArrayAsync();
+            var ys = Enumerable.Range(1, collection).SkipLast(skipCount).ToArray();
+
+            xs.Should().BeEquivalentTo(ys);
+        }
+
+        [Fact]
+        public async Task SkipLastException()
+        {
+            foreach (var item in UniTaskTestException.Throws())
+            {
+                var xs = item.SkipLast(5).ToArrayAsync();
+                await Assert.ThrowsAsync<UniTaskTestException>(async () => await xs);
+            }
+        }
 
         [Theory]
         [InlineData(0, 0)]