diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/CancellationTokenSourceExtensions.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/CancellationTokenSourceExtensions.cs
index 87dcbe7..70fb10b 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/CancellationTokenSourceExtensions.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/CancellationTokenSourceExtensions.cs
@@ -4,6 +4,7 @@ using System.Threading;
 using UnityEngine;
 using Cysharp.Threading.Tasks.Triggers;
 using System;
+using Cysharp.Threading.Tasks.Internal;
 
 namespace Cysharp.Threading.Tasks
 {
@@ -46,6 +47,203 @@ namespace Cysharp.Threading.Tasks
                 cts2.Cancel();
             }, cts);
         }
+
+        // TODO:delete this.
+        public static IDisposable CancelAfterSlim2(this CancellationTokenSource cts, TimeSpan delayTimeSpan)
+        {
+            var timer = PlayerLoopTimer.Create(delayTimeSpan, DelayType.DeltaTime, PlayerLoopTiming.Update, cts.Token, state =>
+            {
+                var x = (CancellationTokenSource)state;
+                x.Cancel();
+            }, cts);
+            timer.Restart();
+
+            return timer;
+        }
+
+        abstract class PlayerLoopTimer : IDisposable, IPlayerLoopItem
+        {
+            readonly CancellationToken cancellationToken;
+            readonly Action<object> timerCallback;
+            readonly object state;
+            readonly PlayerLoopTiming playerLoopTiming;
+
+            bool isPlaying;
+            bool isDisposed;
+
+            protected PlayerLoopTimer(PlayerLoopTiming playerLoopTiming, CancellationToken cancellationToken, Action<object> timerCallback, object state)
+            {
+                this.playerLoopTiming = playerLoopTiming;
+                this.cancellationToken = cancellationToken;
+                this.timerCallback = timerCallback;
+                this.state = state;
+            }
+
+            public static PlayerLoopTimer Create(TimeSpan delayTimeSpan, DelayType delayType, PlayerLoopTiming playerLoopTiming, CancellationToken cancellationToken, Action<object> timerCallback, object state)
+            {
+                switch (delayType)
+                {
+                    case DelayType.UnscaledDeltaTime:
+                        return new IgnoreTimeScalePlayerLoopTimer(delayTimeSpan, playerLoopTiming, cancellationToken, timerCallback, state);
+                    case DelayType.Realtime:
+                        return new RealtimePlayerLoopTimer(delayTimeSpan, playerLoopTiming, cancellationToken, timerCallback, state);
+                    case DelayType.DeltaTime:
+                    default:
+                        return new DeltaTimePlayerLoopTimer(delayTimeSpan, playerLoopTiming, cancellationToken, timerCallback, state);
+                }
+            }
+
+            /// <summary>
+            /// Restart(Reset and Start) timer.
+            /// </summary>
+            public void Restart()
+            {
+                if (isDisposed) throw new ObjectDisposedException(null);
+                if (isPlaying) return;
+
+                ResetCore(); // init state
+                isPlaying = true;
+                PlayerLoopHelper.AddAction(playerLoopTiming, this);
+            }
+
+            /// <summary>
+            /// Stop timer.
+            /// </summary>
+            public void Stop()
+            {
+                isPlaying = false;
+            }
+
+            protected abstract void ResetCore();
+
+            public void Dispose()
+            {
+                isDisposed = true;
+            }
+
+            bool IPlayerLoopItem.MoveNext()
+            {
+                if (isDisposed) return false;
+                if (!isPlaying) return false;
+                if (cancellationToken.IsCancellationRequested) return false;
+
+                if (!MoveNextCore())
+                {
+                    timerCallback(state);
+                    return false;
+                }
+
+                return true;
+            }
+
+            protected abstract bool MoveNextCore();
+        }
+
+        sealed class DeltaTimePlayerLoopTimer : PlayerLoopTimer
+        {
+            int initialFrame;
+            float elapsed;
+            readonly float delayTimeSpan;
+
+            public DeltaTimePlayerLoopTimer(TimeSpan delayTimeSpan, PlayerLoopTiming playerLoopTiming, CancellationToken cancellationToken, Action<object> timerCallback, object state)
+                : base(playerLoopTiming, cancellationToken, timerCallback, state)
+            {
+                this.elapsed = 0.0f;
+                this.delayTimeSpan = (float)delayTimeSpan.TotalSeconds;
+                this.initialFrame = PlayerLoopHelper.IsMainThread ? Time.frameCount : -1;
+            }
+
+            protected override bool MoveNextCore()
+            {
+                if (elapsed == 0.0f)
+                {
+                    if (initialFrame == Time.frameCount)
+                    {
+                        return true;
+                    }
+                }
+
+                elapsed += Time.deltaTime;
+                if (elapsed >= delayTimeSpan)
+                {
+                    return false;
+                }
+
+                return true;
+            }
+
+            protected override void ResetCore()
+            {
+                elapsed = 0.0f;
+            }
+        }
+
+        sealed class IgnoreTimeScalePlayerLoopTimer : PlayerLoopTimer
+        {
+            int initialFrame;
+            float elapsed;
+            readonly float delayTimeSpan;
+
+            public IgnoreTimeScalePlayerLoopTimer(TimeSpan delayTimeSpan, PlayerLoopTiming playerLoopTiming, CancellationToken cancellationToken, Action<object> timerCallback, object state)
+                : base(playerLoopTiming, cancellationToken, timerCallback, state)
+            {
+                this.elapsed = 0.0f;
+                this.delayTimeSpan = (float)delayTimeSpan.TotalSeconds;
+                this.initialFrame = PlayerLoopHelper.IsMainThread ? Time.frameCount : -1;
+            }
+
+            protected override bool MoveNextCore()
+            {
+                if (elapsed == 0.0f)
+                {
+                    if (initialFrame == Time.frameCount)
+                    {
+                        return true;
+                    }
+                }
+
+                elapsed += Time.unscaledDeltaTime;
+                if (elapsed >= delayTimeSpan)
+                {
+                    return false;
+                }
+
+                return true;
+            }
+
+            protected override void ResetCore()
+            {
+                elapsed = 0.0f;
+            }
+        }
+
+        sealed class RealtimePlayerLoopTimer : PlayerLoopTimer
+        {
+            ValueStopwatch stopwatch;
+            readonly long delayTimeSpanTicks;
+
+            public RealtimePlayerLoopTimer(TimeSpan delayTimeSpan, PlayerLoopTiming playerLoopTiming, CancellationToken cancellationToken, Action<object> timerCallback, object state)
+                : base(playerLoopTiming, cancellationToken, timerCallback, state)
+            {
+                this.stopwatch = ValueStopwatch.StartNew();
+                this.delayTimeSpanTicks = delayTimeSpan.Ticks;
+            }
+
+            protected override bool MoveNextCore()
+            {
+                if (stopwatch.ElapsedTicks >= delayTimeSpanTicks)
+                {
+                    return false;
+                }
+
+                return true;
+            }
+
+            protected override void ResetCore()
+            {
+                this.stopwatch = ValueStopwatch.StartNew();
+            }
+        }
     }
 }