diff --git a/python/mlc/_cython/core.pyx b/python/mlc/_cython/core.pyx
index ca3060f..ad41ed7 100644
--- a/python/mlc/_cython/core.pyx
+++ b/python/mlc/_cython/core.pyx
@@ -6,8 +6,17 @@ from libcpp.vector cimport vector
 from libc.stdint cimport int8_t, int16_t, int32_t, int64_t, uint8_t, uint16_t, uint32_t, uint64_t
 from libc.stdlib cimport malloc, free
 from numbers import Integral, Number
-from cpython cimport Py_DECREF, Py_INCREF, PyCapsule_IsValid, PyCapsule_GetPointer, PyCapsule_SetName, PyCapsule_New
 from . import base
+from cpython.pycapsule cimport (
+    PyCapsule_IsValid,
+    PyCapsule_GetPointer,
+    PyCapsule_SetName,
+    PyCapsule_New,
+)
+
+cdef extern from "Python.h":
+    void Py_IncRef(object)
+    void Py_DecRef(object)
 
 Ptr = base.Ptr
 PyCode_NewEmpty = ctypes.pythonapi.PyCode_NewEmpty
@@ -417,21 +426,17 @@ cdef class PyAny:
                 raise e.with_traceback(None)
         return _any_c2py_no_inc_ref(c_ret)
 
-cdef class Str(str):
-    cdef MLCAny _mlc_any
-    __slots__ = ()
-
-    def __cinit__(self):
-        self._mlc_any = _MLCAnyNone()
 
-    def __init__(self, value):
-        cdef str value_unicode = self
-        cdef bytes value_c = str_py2c(value_unicode)
-        self._mlc_any = _MLCAnyRawStr(value_c)
-        _check_error(_C_AnyInplaceViewToOwned(&self._mlc_any))
+class Str(str):
+    __slots__ = ("_pyany",)
 
-    def __dealloc__(self):
-        _check_error(_C_AnyDecRef(&self._mlc_any))
+    def __new__(cls, value: str):
+        cdef PyAny pyany = PyAny()
+        self = super().__new__(cls, value)
+        self._pyany = pyany
+        pyany._mlc_any = _MLCAnyRawStr(str_py2c(value))
+        _check_error(_C_AnyInplaceViewToOwned(&pyany._mlc_any))
+        return self
 
     def __reduce__(self):
         return (Str, (str(self),))
@@ -541,7 +546,7 @@ cdef inline object _any_c2py_no_inc_ref(const MLCAny x):
     cdef int32_t type_index = x.type_index
     cdef MLCStr* mlc_str = NULL
     cdef PyAny any_ret
-    cdef Str str_ret
+    cdef object str_ret
     if type_index == kMLCNone:
         return None
     elif type_index == kMLCBool:
@@ -556,8 +561,10 @@ cdef inline object _any_c2py_no_inc_ref(const MLCAny x):
         return str_c2py(x.v.v_str)
     elif type_index == kMLCStr:
         mlc_str = <MLCStr*>(x.v.v_obj)
+        any_ret = PyAny()
+        any_ret._mlc_any = x
         str_ret = Str.__new__(Str, str_c2py(mlc_str.data[:mlc_str.length]))
-        str_ret._mlc_any = x
+        str_ret._pyany = any_ret
         return str_ret
     elif type_index == kMLCOpaque:
         return <object>((<MLCOpaque*>(x.v.v_obj)).handle)
@@ -572,7 +579,7 @@ cdef inline object _any_c2py_inc_ref(MLCAny x):
     cdef int32_t type_index = x.type_index
     cdef MLCStr* mlc_str = NULL
     cdef PyAny any_ret
-    cdef Str str_ret
+    cdef object str_ret
     if type_index == kMLCNone:
         return None
     elif type_index == kMLCBool:
@@ -587,8 +594,10 @@ cdef inline object _any_c2py_inc_ref(MLCAny x):
         return str_c2py(x.v.v_str)
     elif type_index == kMLCStr:
         mlc_str = <MLCStr*>(x.v.v_obj)
+        any_ret = PyAny()
+        any_ret._mlc_any = x
         str_ret = Str.__new__(Str, str_c2py(mlc_str.data[:mlc_str.length]))
-        str_ret._mlc_any = x
+        str_ret._pyany = any_ret
         _check_error(_C_AnyIncRef(&x))
         return str_ret
     elif type_index == kMLCOpaque:
@@ -624,11 +633,11 @@ cdef inline PyAny _pyany_from_opaque(object x):
     args[0] = _MLCAnyPtr(<uint64_t>(<void*>x))
     args[1] = _MLCAnyPtr(<uint64_t>(<void*>_pyobj_deleter))
     args[2] = _MLCAnyRawStr(type_name)
-    Py_INCREF(x)
+    Py_IncRef(x)
     try:
         _func_call_impl_with_c_args(_OPAQUE_INIT, 3, args, &ret._mlc_any)
     except:  # no-cython-lint
-        Py_DECREF(x)
+        Py_DecRef(x)
         raise
     return ret
 
@@ -677,7 +686,7 @@ cdef inline MLCAny _any_py2c(object x, list temporary_storage):
     elif isinstance(x, PyAny):
         y = (<PyAny>x)._mlc_any
     elif isinstance(x, Str):
-        y = (<Str>x)._mlc_any
+        y = (<PyAny>(x._pyany))._mlc_any
     elif isinstance(x, bool):
         y = _MLCAnyBool(<bint>x)
     elif isinstance(x, Integral):
@@ -729,7 +738,7 @@ cdef inline MLCAny _any_py2c_dict(tuple x, list temporary_storage):
 cdef void _pyobj_deleter(void* handle) noexcept nogil:
     with gil:
         try:
-            Py_DECREF(<object>(handle))
+            Py_DecRef(<object>(handle))
         except Exception as exception:
             # TODO(@junrushao): Will need to handle exceptions more gracefully
             print(f"Error in _pyobj_deleter: {exception}")
@@ -767,7 +776,7 @@ cdef inline int32_t _func_safe_call_impl(
 
 cdef inline PyAny _pyany_from_func(object py_func):
     cdef PyAny ret = PyAny()
-    Py_INCREF(py_func)
+    Py_IncRef(py_func)
     _check_error(_C_FuncCreate(<void*>(py_func), _pyobj_deleter, _func_safe_call, &ret._mlc_any))
     return ret