The Hero and the Sage, Reincarnated and Engaged: Volume 5

World saved and invasion quelled, Raid and Eluria have every reason to breathe a sigh of relief and pat themselves on the back—but their work is far from over. Past mistakes must be rectified, old grievances must be settled, and most of all, an entire abandoned timeline still needs saving! With countless lives once again resting on their shoulders, the most powerful couple sets out into a ravaged world where everything they know only remains in tragic traces and bittersweet memories. Many problems await on the other side—from the devastated environment to the vicious empire coming after their heads—but surprisingly, the key to it all has already been by their side this entire time...in the form of a certain ordinary girl from the boonies!

[From J-Novel Club]