diff --git a/Services/SyncService.cs b/Services/SyncService.cs
index ca6c9b9..691eb37 100644
--- a/Services/SyncService.cs
+++ b/Services/SyncService.cs
@@ -6,12 +6,6 @@
 
 public sealed class SyncService(AppDbContext dbContext)
 {
-    private static readonly string[] DefaultKeywords =
-    {
-        "ユウリ","セレナ","ヒカリ","リーリエ","ミヅキ","メイ","マリィ","ルチア","コトネ",
-        "大苦戦","敗北","拘束","差分","差分セット"
-    };
-
     private readonly AppDbContext _dbContext = dbContext;
 
     public async Task<int> SyncFanboxFoldersAsync(
@@ -27,6 +21,7 @@
         var inserted = 0;
 
         var pending = new List<FanboxFolder>();
+        var existingKeywords = await LoadExistingKeywordsAsync(cancellationToken);
 
         foreach (var dir in Directory.GetDirectories(root))
         {
@@ -46,7 +41,7 @@
                 continue;
 
             var title = folderName.Substring(11);
-            var keywordsStr = BuildKeywords(title);
+            var keywordsStr = BuildKeywords(title, existingKeywords);
             var fileCount = Directory.GetFiles(dir).Length;
 
             var exists = await _dbContext.FanboxFolders.AsNoTracking().AnyAsync(
@@ -75,7 +70,7 @@
         return inserted;
     }
 
-    private static string? BuildKeywords(string title)
+    private static string? BuildKeywords(string title, IReadOnlyCollection<string> existingKeywords)
     {
         var hit = new HashSet<string>(StringComparer.Ordinal);
 
@@ -98,7 +93,7 @@
                 hit.Add(w);
         }
 
-        foreach (var k in DefaultKeywords)
+        foreach (var k in existingKeywords)
         {
             if (title.Contains(k, StringComparison.Ordinal))
                 hit.Add(k);
@@ -106,4 +101,27 @@
 
         return hit.Count > 0 ? string.Join(",", hit) : null;
     }
+
+    private async Task<IReadOnlyCollection<string>> LoadExistingKeywordsAsync(CancellationToken cancellationToken)
+    {
+        var keywordLists = await _dbContext.FanboxFolders.AsNoTracking()
+            .Select(x => x.Keywords)
+            .Where(x => x != null && x != string.Empty)
+            .Distinct()
+            .ToListAsync(cancellationToken);
+
+        var keywords = new HashSet<string>(StringComparer.Ordinal);
+        foreach (var list in keywordLists)
+        {
+            if (string.IsNullOrWhiteSpace(list))
+                continue;
+
+            foreach (var keyword in list.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries))
+            {
+                keywords.Add(keyword);
+            }
+        }
+
+        return keywords;
+    }
 }
diff --git a/Services/ThumbnailService.cs b/Services/ThumbnailService.cs
index 7b10351..3ceb9a7 100644
--- a/Services/ThumbnailService.cs
+++ b/Services/ThumbnailService.cs
@@ -9,7 +9,7 @@
         ".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp"
     };
 
-    private const int MinSize = 250;
+    private const int MinSize = 640;
     private const int JpegQuality = 82;
     private readonly string? _rootPath;
     private readonly string? _thumbnailRoot;