Reincarnated Into a Game as the Hero's Friend: Running the Kingdom Behind the Scenes Novel Volume 6 was written by Yuki Suzuki and illustrated by Sanshouuo.

Having devised and executed the perfect strategy to defeat Demon Commander Gezarius, Werner von Zehrfeld makes a gallant return to the capital alongside his friend, the Hero Mazel. However, there is no time to rest as Crown Prince Hubertus commands him to investigate a secret underground library. The number of books stored there is incredible, but clues to even deeper secrets may lie within. Meanwhile, sinister forces are trying to find ways to use the Hero's powers for themselves. Is it all too much for the once-average office worker to handle?