A bit more information: The S-31 Kurowashi ("Black Eagle") was a fictional aircraft design that appeared in Japanese Sora magazine, 1944...
The artists web site is here:
http://digitalaviationart.com/skyraider3d/jsp_profiles_2.htm
Skyraiders3D Aviation art. some funky stuff!
Addemdum: to quote...'The S-31 Kurowashi (Black Eagle) was probably the most spectacular. It appeared in a Japanese aviation magazine (Sora, in a regular ection called 'dreams of future designers') & it doesn't seem to have gone much further than initial concept and may have been speculative or an attempt at disinformation. It looks like a Do.335 on steroids. It would have had four 2,500hp X-24 engines, two in the nose, two in the tail. It would have had eight 7.7mm guns in four pairs & four 23mm cannon (not actually avaialbe for mounting on aircraft at the time) mounted on barbettes in the wings, remotely controlled from defensive positions in the fuselage. It would have been 5.88m high, with a length of 21.09m & a wingspan of 32.82m, very similar to a B-17.'
http://www.geocities.jp/ramopcommand/_geo_contents_/070504/kakuusono3.html
A bit more here on related projects, and some wild photographs....and here...
http://http://www.geocities.jp/ramopcommand/_geo_contents_/070504/kakuusono3.html
Type: Heavy Bomber
Crew: Five
Powerplant: Four 24-cylinder, liquid-cooled X-engines, each developing 2,500hp, each pair driving two, metal, 3-bladed contra-rotating propellers
Dimensions
Span: 32.82m/107.7ft
Length: 21.09m/69.2ft
Height: 5.88m/19.3ft
Wing Area: 133.00 sq.m/1,431.6 sq.ft
Weights
Loaded: 17,850kg/39,352lb
Performance
Max speed: 690km/h/429mph
Cruise speed: 589km/h/366mph
Landing speed: 145km/h/90mph
Range: 5,900km/3,666 miles
Ceiling: 15,100m/49,540ft
Fuel Weight: 8,000kg/17,636lb
Armament
Eight 7.7mm machine guns and four 23mm cannons; up to 8,000kg (17,636lb) of bombs
The plane had a novel defensive armament scheme, using remote fired ball turrets in the leading and trailing edge of the wings.(note sighted by television ...Ambitious!)
Thats about all that fell out on a quick search. I'll have to see if there is any thing in the microfisch archive. I remember seeing an index of 'Sora'(Eagle?) magazine.