diff --git a/iamai/__init__.py b/iamai/__init__.py
index 7fac060c..49f0676d 100644
--- a/iamai/__init__.py
+++ b/iamai/__init__.py
@@ -11,7 +11,6 @@
 from iamai.dependencies import Depends
 from iamai.event import Event, MessageEvent
 from iamai.plugin import Plugin
-from iamai._core import sum_as_string
 
 __all__ = [
     "Adapter",
@@ -21,5 +20,4 @@
     "Event",
     "MessageEvent",
     "Plugin",
-    "Core",
 ]