The standard Honda steel sprockets come complete with the special nuts pressed into them. They can have a thin hex nut shape or, just two flats for an open end spanner.
When I fitted the race aluminium sprockets to my bikes I took the special nuts out of the original steel sprockets.
Most of the time they turn in their mountings and pull out easily. Sometimes they need pressing or driving out.
The MC18 is different. It has five special cap head bolts that pass through the sprocket & screw into the aluminium carrier.