diff --git a/src/dec/kirikiri/xp3_archive_decoder_plugins.cc b/src/dec/kirikiri/xp3_archive_decoder_plugins.cc
index c757077da..bbcc91ddb 100644
--- a/src/dec/kirikiri/xp3_archive_decoder_plugins.cc
+++ b/src/dec/kirikiri/xp3_archive_decoder_plugins.cc
@@ -125,6 +125,16 @@ Xp3ArchiveDecoder::Xp3ArchiveDecoder()
                 data[0x13] ^= 1;
         }));
 
+    plugin_manager.add(
+        "gsenjou", "G-Senjou No Maou",
+        create_simple_plugin([](bstr &data, u32 key)
+        {
+            key >>= 12;
+
+            for (int i = 5; i < data.size(); i++)
+                data[i] ^= key;
+        }));
+
     plugin_manager.add(
         "fha", "Fate/Hollow Ataraxia",
         create_cxdec_plugin(