Saw that this theme isn't anywhere on youtube so I thought to upload it myself. Love this, sounds exactly like something straight from a fighting game character select screen.
In NG Black it can be heard in the part where Ryu shoots down the helicopter and leaves the military base. I have also failed looking for it for a long time, even better I recorded it directly from the title of the Sigma of the Master Collection, because it is nowhere to be found, it does not even come in the soundtrack of the game. I thank you for uploading it!
I come to update the comment, because a friend found it, so I came to pass it to you, here it is, and in extended version, enjoy. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-FJ34hgizwPY.html