from fastapi import APIRouter, HTTPException

users = []  # In-memory storage

router = APIRouter()

@router.post("/logout")
async def logout(request):
    """Logout endpoint"""
    if request.method != "POST":
        raise HTTPException(status_code=405, detail="Method Not Allowed")

    # Logout logic here
    return {
        "message": "Logout successful",
        "method": "POST",
        "_verb": "post"
    }
```

This is a FastAPI endpoint that handles a POST request to the `/logout` path. It adheres to the provided rules and examples, including:

1. Using the `@router.post` decorator to define a POST endpoint.
2. Checking if the request method is POST, and raising a 405 Method Not Allowed error if not.
3. Returning a response with the required fields: `"message"`, `"method"`, and `"_verb"`.
4. Placeholder for logout logic (e.g., invalidating session, clearing cookies, etc.).

Note that the actual logout functionality is not implemented here, as it would depend on the specific authentication mechanism used in the application.