Well, the next logical step was to launch a Google Search using 五十嵐周正 instead of Igarashi Chikamasa, here are my first results :

He graduated from the Naval Academy of Etajima, class 56, in march 1928 (he is from Tsuchiura, about 50 km northeast of Tokyo)...
http://www.niehorster.org/014_japan ...

Sadly, in the game, Cdr Igarashi Chikamasa has the skills of a torpedo bomber pilot, and I haven't found a way yet to change them in the editor, or if it is even possible.

Hello Peiper1944, allow me to put my 2¢ in... I have a copy of Hata's Japanese Naval Aces and Fighter Units in World War II , and under Chitose Air Group (pp.103-5), CAPT Ōhashi Fujiro is indeed the commanding officer at Roi just before the start of the war...
But at the end of november 1941, some ...

From René J Francillon, Japanese Aircraft of the Pacific War (1970), p.460...

« A final bomber version providing crew and fuel tank protection was under development when Japan capitulated. Intended to be powered by a 1,825 hp Nakajima NK9C Homare 12 eighteen-cylinder air-cooled radial, the D4Y5 was ...