diff --git a/sunbeam-python/sunbeam/storage/backends/toyouacs5000/__init__.py b/sunbeam-python/sunbeam/storage/backends/toyouacs5000/__init__.py
new file mode 100644
index 000000000..b994e3755
--- /dev/null
+++ b/sunbeam-python/sunbeam/storage/backends/toyouacs5000/__init__.py
@@ -0,0 +1,4 @@
+# SPDX-FileCopyrightText: 2026 - Canonical Ltd
+# SPDX-License-Identifier: Apache-2.0
+
+"""Toyou ACS5000 backend for Sunbeam storage."""
diff --git a/sunbeam-python/sunbeam/storage/backends/toyouacs5000/backend.py b/sunbeam-python/sunbeam/storage/backends/toyouacs5000/backend.py
new file mode 100644
index 000000000..daf5cca63
--- /dev/null
+++ b/sunbeam-python/sunbeam/storage/backends/toyouacs5000/backend.py
@@ -0,0 +1,118 @@
+# SPDX-FileCopyrightText: 2026 - Canonical Ltd
+# SPDX-License-Identifier: Apache-2.0
+"""Vendor backend implementation using base step classes."""
+
+import logging
+from enum import StrEnum
+from typing import Annotated
+
+from pydantic import Field
+from rich.console import Console
+
+from sunbeam.core.manifest import StorageBackendConfig
+from sunbeam.storage.base import StorageBackendBase
+from sunbeam.storage.models import SecretDictField
+
+LOG = logging.getLogger(__name__)
+console = Console()
+
+
+class Protocol(StrEnum):
+    """Enumeration of valid protocol types."""
+
+    FC = "fc"
+    ISCSI = "iscsi"
+
+
+class Toyouacs5000Config(StorageBackendConfig):
+    """Configuration model for Acs5000 backend.
+
+    This model includes ALL configuration options for the backend.
+    Additional configuration can be managed dynamically through the charm.
+    """
+
+    # Mandatory connection parameters (required: true in spec)
+    san_ip: Annotated[str, Field(description="IP address of SAN controller")]
+    san_login: Annotated[
+        str,
+        Field(description="Username for SAN controller"),
+        SecretDictField(field="san-login"),
+    ]
+    san_password: Annotated[
+        str,
+        Field(description="Password for SAN controller"),
+        SecretDictField(field="san-password"),
+    ]
+
+    # Optional backend configuration (required: false in spec)
+    protocol: Annotated[
+        Protocol | None,
+        Field(description="Protocol selector: fc, iscsi."),
+    ] = None
+
+    # Storage management options
+    acs5000_volpool_name: Annotated[
+        str | None,
+        Field(
+            description=(
+                "Comma-separated list of storage system storage pools for volumes."
+            )
+        ),
+    ] = None
+    acs5000_copy_interval: Annotated[
+        int | None,
+        Field(
+            description=(
+                "When volume copy task is going on, refresh volume status interval"
+            )
+        ),
+    ] = None
+    acs5000_multiattach: Annotated[
+        bool | None,
+        Field(description="Enable multi-attach for volumes with no host limit."),
+    ] = None
+    san_thin_provision: Annotated[
+        bool | None,
+        Field(description="Use thin provisioning for SAN volumes?"),
+    ] = None
+    use_multipath_for_image_xfer: Annotated[
+        bool | None,
+        Field(description="Enable multipathing for image transfer operations."),
+    ] = None
+
+
+class Toyouacs5000Backend(StorageBackendBase):
+    """Acs5000 backend implementation."""
+
+    backend_type = "toyouacs5000"
+    display_name = "Acs5000 FC/iSCSI"
+    generally_available = True
+
+    @property
+    def charm_name(self) -> str:
+        """Return the charm application name."""
+        return "cinder-volume-toyouacs5000"
+
+    @property
+    def charm_channel(self) -> str:
+        """Return the default charm channel."""
+        return "latest/edge"
+
+    @property
+    def charm_revision(self) -> str | None:
+        """Return a pinned charm revision, if any."""
+        return None
+
+    @property
+    def charm_base(self) -> str:
+        """Return the target base for this charm."""
+        return "ubuntu@24.04"
+
+    @property
+    def supports_ha(self) -> bool:
+        """Whether this backend supports HA deployments."""
+        return False
+
+    def config_type(self) -> type[StorageBackendConfig]:
+        """Return the configuration model type for this backend."""
+        return Toyouacs5000Config
diff --git a/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py b/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py
index 80d3d8ef5..cb5064275 100644
--- a/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py
+++ b/sunbeam-python/tests/unit/sunbeam/storage/backends/conftest.py
@@ -9,6 +9,7 @@
 from sunbeam.storage.backends.dellsc.backend import DellSCBackend
 from sunbeam.storage.backends.hitachi.backend import HitachiBackend
 from sunbeam.storage.backends.purestorage.backend import PureStorageBackend
+from sunbeam.storage.backends.toyouacs5000.backend import Toyouacs5000Backend
 
 
 @pytest.fixture
@@ -29,19 +30,28 @@ def dellsc_backend():
     return DellSCBackend()
 
 
+@pytest.fixture
+def toyouacs5000_backend():
+    """Provide a Toyou ACS5000 backend instance."""
+    return Toyouacs5000Backend()
+
+
 @pytest.fixture
 def dellpowerstore_backend():
     """Provide a Dell PowerStore backend instance."""
     return DellPowerstoreBackend()
 
 
-@pytest.fixture(params=["hitachi", "purestorage", "dellsc", "dellpowerstore"])
+@pytest.fixture(
+    params=["hitachi", "purestorage", "dellsc", "toyouacs5000", "dellpowerstore"]
+)
 def any_backend(request):
     """Parametrized fixture that provides each backend type."""
     backends = {
         "hitachi": HitachiBackend(),
         "purestorage": PureStorageBackend(),
         "dellsc": DellSCBackend(),
+        "toyouacs5000": Toyouacs5000Backend(),
         "dellpowerstore": DellPowerstoreBackend(),
     }
     return backends[request.param]
diff --git a/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py
index def51a0e8..182eed1c1 100644
--- a/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py
+++ b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_common.py
@@ -157,13 +157,18 @@ def backend(self, any_backend):
 
 
 def test_all_backends_have_unique_types(
-    hitachi_backend, purestorage_backend, dellsc_backend, dellpowerstore_backend
+    hitachi_backend,
+    purestorage_backend,
+    dellsc_backend,
+    toyouacs5000_backend,
+    dellpowerstore_backend,
 ):
     """Test that all backends have unique type identifiers."""
     backends = [
         hitachi_backend,
         purestorage_backend,
         dellsc_backend,
+        toyouacs5000_backend,
         dellpowerstore_backend,
     ]
     types = [b.backend_type for b in backends]
@@ -173,13 +178,18 @@ def test_all_backends_have_unique_types(
 
 
 def test_all_backends_have_unique_charm_names(
-    hitachi_backend, purestorage_backend, dellsc_backend, dellpowerstore_backend
+    hitachi_backend,
+    purestorage_backend,
+    dellsc_backend,
+    toyouacs5000_backend,
+    dellpowerstore_backend,
 ):
     """Test that all backends have unique charm names."""
     backends = [
         hitachi_backend,
         purestorage_backend,
         dellsc_backend,
+        toyouacs5000_backend,
         dellpowerstore_backend,
     ]
     charm_names = [b.charm_name for b in backends]
@@ -196,6 +206,7 @@ def test_all_backends_have_unique_charm_names(
         ("hitachi", "hitachi"),
         ("purestorage", "purestorage"),
         ("dellsc", "dellsc"),
+        ("toyouacs5000", "toyouacs5000"),
         ("dellpowerstore", "dellpowerstore"),
     ],
 )
@@ -211,6 +222,7 @@ def test_backend_types_match_expected(any_backend, backend_type, expected_type):
         ("hitachi", "cinder-volume-hitachi"),
         ("purestorage", "cinder-volume-purestorage"),
         ("dellsc", "cinder-volume-dellsc"),
+        ("toyouacs5000", "cinder-volume-toyouacs5000"),
         ("dellpowerstore", "cinder-volume-dellpowerstore"),
     ],
 )
diff --git a/sunbeam-python/tests/unit/sunbeam/storage/backends/test_toyouacs5000.py b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_toyouacs5000.py
new file mode 100644
index 000000000..e339a4050
--- /dev/null
+++ b/sunbeam-python/tests/unit/sunbeam/storage/backends/test_toyouacs5000.py
@@ -0,0 +1,85 @@
+# SPDX-FileCopyrightText: 2026 - Canonical Ltd
+# SPDX-License-Identifier: Apache-2.0
+
+"""Tests for Toyou ACS5000 backend."""
+
+import pytest
+from pydantic import ValidationError
+
+from sunbeam.storage.models import SecretDictField
+from tests.unit.sunbeam.storage.backends.test_common import BaseBackendTests
+
+
+class TestToyouacs5000Backend(BaseBackendTests):
+    """Tests for Toyou ACS5000 backend."""
+
+    @pytest.fixture
+    def backend(self, toyouacs5000_backend):
+        """Provide Toyou ACS5000 backend instance."""
+        return toyouacs5000_backend
+
+    def test_backend_type_is_toyouacs5000(self, backend):
+        """Test that backend type is 'toyouacs5000'."""
+        assert backend.backend_type == "toyouacs5000"
+
+    def test_charm_name_is_toyouacs5000_charm(self, backend):
+        """Test that charm name is cinder-volume-toyouacs5000."""
+        assert backend.charm_name == "cinder-volume-toyouacs5000"
+
+    def test_display_name_is_protocol_agnostic(self, backend):
+        """Test that display name reflects FC and iSCSI support."""
+        assert backend.display_name == "Acs5000 FC/iSCSI"
+
+    def test_config_has_expected_fields(self, backend):
+        """Test that Toyou ACS5000 config exposes expected fields."""
+        fields = backend.config_type().model_fields
+        for field in ("san_ip", "protocol", "san_login", "san_password"):
+            assert field in fields, f"Expected field {field} not found in config"
+
+    def test_config_enforces_required_fields(self, backend):
+        """Test that mandatory Toyou ACS5000 config fields are required."""
+        fields = backend.config_type().model_fields
+        for field in ("san_ip", "san_login", "san_password"):
+            assert fields[field].is_required(), (
+                f"Field {field} should be required in config"
+            )
+
+    def test_sensitive_fields_are_marked_secret(self, backend):
+        """Test that SAN credentials are marked as secret."""
+        config_class = backend.config_type()
+        for field_name in ("san_login", "san_password"):
+            field = config_class.model_fields.get(field_name)
+            assert field is not None
+            assert any(isinstance(m, SecretDictField) for m in field.metadata), (
+                f"{field_name} should be marked as secret"
+            )
+
+
+class TestToyouacs5000ConfigValidation:
+    """Test Toyou ACS5000 config validation behavior."""
+
+    def test_protocol_rejects_invalid_value(self, toyouacs5000_backend):
+        """Test that protocol rejects values other than fc/iscsi."""
+        config_class = toyouacs5000_backend.config_type()
+        with pytest.raises(ValidationError):
+            config_class.model_validate(
+                {
+                    "san-ip": "192.168.1.1",
+                    "san-login": "admin",
+                    "san-password": "secret",
+                    "protocol": "nvme",
+                }
+            )
+
+    def test_protocol_accepts_fc(self, toyouacs5000_backend):
+        """Test that protocol accepts fc."""
+        config_class = toyouacs5000_backend.config_type()
+        config = config_class.model_validate(
+            {
+                "san-ip": "192.168.1.1",
+                "san-login": "admin",
+                "san-password": "secret",
+                "protocol": "fc",
+            }
+        )
+        assert config.protocol == "fc"