Gungriffon Complete File
From Sega Retro
So, this one's driving me a little batty--the publisher is listed as 「光栄」(Koei), but trying to understand if this is the same Koei as Koei is a little difficult. Finding non-gaming books by this Koei is straightforward: 光栄出版部 also returns results for manga and, oddly enough, a WWII naval battle book. On the other hand, if you look at this article on Winning Post 3, a game made by Koei, you see that a book by Koei publishing is listed as the publisher for the Winning Post 3 guide book.
All that to say I have no idea if they're the same but leaning towards yes. - Scarred Sun (talk) 11:43, 29 November 2020 (EST)