A fictional flying boat in the Studio Ghibli movie and manga Kurenai no Buta. Based on the real-life Macchi M.33, it is a scarlet-red open-cockpit monoplane with a single overwing-mounted engine, a yellow underside and a fin flash that displays the Royal Italian Air Force tricolore overlaid with the coat of arms of the city of Genoa.
There are three variations of the S.21. The original version can be seen in post #705377; post #740389 shows the version with the uprated engine and chin-type radiator. This also has provision for seating a single passenger in front. A third version with contra-rotating propellers was included with a discarded movie epilogue sequence. The S.21 was armed with two 7.92mm machine guns.
