Only extant Seiran (Clear Sky Storm) on display at Udvar-Hazy Center. This is the last of 28 built that was ferried by Lt. Kazuo Akatsuka to Yokosuka and surrendered in 1945. Designed by Toshio Ozaki who planned the B7A Ryūsei, the floatplane was powered by a 12-cyl liquid-cooled 1,400 hp Atsuta 32 engine that was a licence-built DB601A. These aircraft of 631 Kokutai were to be launched via catapult from 122 m I-400-class submarines capable of carrying three Seirans. Operations were planned to bomb Panama Canal, the US fleet at Ulithi Atoll and US cities, forestalled by the end of the war.