The Faraway Paladin: The Lord of the Rust Mountains: Primus by Kanata Yanagino

It’s been some time since Will became the Faraway Paladin. Will and Menel have defeated the demons and chimera who wrought havoc on the lives of the villagers of Beast Woods, and smiles are finally starting to return to everyone’s faces again.
But order has not completely been restored to this faraway land; strange things are happening, starting with plants blooming out of season and dying at random. At Duke Ethel’s request, Will and Menel are off to investigate, not knowing that their journey will lead them to an ominous prophecy and the Rust Mountains, the capital of the dwarves.