Sotoichi Saito of Tsuruoka City, Yamagata Prefecture, had been involved in the development of balloon flight since 1889. In 1910 he bought a 50hp Gnome engine from France so that he could study aero-engines. He later acquired a patent for a ‘Flying Machine’ and manufactured an aircraft resembling a Bleriot monoplane. Helping with this project was Shotaro Ueda. Single-engine monoplane. Wooden structure with fabric-covered wing and uncovered fuselage structure.

The aeroplane contained some rather innovative features. For protection against inflight fire, the fuel tank was installed on struts high above the rear fuselage at a considerable distance from the engine. Another feature was that in the event of an inflight emergency, a cable could be pulled, causing the fuselage and engine to separate from the wings leaving the pilot still seated on the wing section which was to act as a parachute.

Saito named his aeroplane the Saigai, an acronym derived from his own name. In june 1912 he tested the aeroplane on the dry bed of the Akagawa River in Tsuruoka City. The aeroplane, piloted by Suketaro Koya, was put on a special railway track for take off. Koya was probably selected because of his engine experience in operating the Mogami Maru river boat. Soon after becoming airborne, Koya felt that further flight would be risky and pulled the emergency cord, thus destroying the aeroplane. The Gnome engine was salvaged and installed in the Tamai 3 Aeroplane in 1917, in which the pilot, Seitaro Tamai, was killed. The engine then passed to Shigesaburo Torigai, and still later was installed in the Tsurubane No.2 Aeroplane of Otojiro Itoh, which made the first loop by a Japanese civil aeroplane when piloted by Toyotaro Yamagata in 1918.

Engine: 50hp Gnome
Propeller: two-blade wood
Span: 10.30m (33ft 9 1/2in)
Length: 9.10m (29ft 10 1/4in)
Loaded weight: 560kg (1,234Ib)