diff --git a/src/arcaea_offline_ocr/scenarios/b30/base.py b/src/arcaea_offline_ocr/scenarios/b30/base.py
new file mode 100644
index 0000000..7d3492a
--- /dev/null
+++ b/src/arcaea_offline_ocr/scenarios/b30/base.py
@@ -0,0 +1,22 @@
+from abc import abstractmethod
+from typing import TYPE_CHECKING, List
+
+from arcaea_offline_ocr.scenarios.base import OcrScenario, OcrScenarioResult
+
+if TYPE_CHECKING:
+    from arcaea_offline_ocr.types import Mat
+
+
+class Best30Scenario(OcrScenario):
+    @abstractmethod
+    def components(self, img: "Mat", /) -> List["Mat"]: ...
+
+    @abstractmethod
+    def result(self, component_img: "Mat", /, *args, **kwargs) -> OcrScenarioResult: ...
+
+    @abstractmethod
+    def results(self, img: "Mat", /, *args, **kwargs) -> List[OcrScenarioResult]:
+        """
+        Commonly a shorthand for `[self.result(comp) for comp in self.components(img)]`
+        """
+        ...
diff --git a/src/arcaea_offline_ocr/scenarios/base.py b/src/arcaea_offline_ocr/scenarios/base.py
new file mode 100644
index 0000000..35e13c9
--- /dev/null
+++ b/src/arcaea_offline_ocr/scenarios/base.py
@@ -0,0 +1,38 @@
+from abc import ABC
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Sequence, Optional
+
+from arcaea_offline_ocr.providers import ImageIdProviderResult
+
+
+@dataclass(kw_only=True)
+class OcrScenarioResult:
+    song_id: str
+    rating_class: int
+    score: int
+
+    song_id_results: Sequence[ImageIdProviderResult] = field(default_factory=lambda: [])
+    partner_id_results: Sequence[ImageIdProviderResult] = field(
+        default_factory=lambda: []
+    )
+
+    pure: Optional[int] = None
+    pure_inaccurate: Optional[int] = None
+    pure_early: Optional[int] = None
+    pure_late: Optional[int] = None
+    far: Optional[int] = None
+    far_inaccurate: Optional[int] = None
+    far_early: Optional[int] = None
+    far_late: Optional[int] = None
+    lost: Optional[int] = None
+
+    played_at: Optional[datetime] = None
+    max_recall: Optional[int] = None
+    clear_status: Optional[int] = None
+    clear_type: Optional[int] = None
+    modifier: Optional[int] = None
+
+
+class OcrScenario(ABC):
+    pass
diff --git a/src/arcaea_offline_ocr/scenarios/device/base.py b/src/arcaea_offline_ocr/scenarios/device/base.py
new file mode 100644
index 0000000..070bfb0
--- /dev/null
+++ b/src/arcaea_offline_ocr/scenarios/device/base.py
@@ -0,0 +1,8 @@
+from abc import abstractmethod
+
+from arcaea_offline_ocr.scenarios.base import OcrScenario, OcrScenarioResult
+
+
+class DeviceScenarioBase(OcrScenario):
+    @abstractmethod
+    def result(self) -> OcrScenarioResult: ...