diff --git a/internal/theme/usecase.go b/internal/theme/usecase.go
new file mode 100644
index 0000000..99c646a
--- /dev/null
+++ b/internal/theme/usecase.go
@@ -0,0 +1,10 @@
+package theme
+
+import (
+	"context"
+	"html/template"
+)
+
+type UseCase interface {
+	Do(ctx context.Context) (*template.Template, error)
+}