Kamen Rider Saber Emotional Dragon was able to defeat Kamen Rider Falchion and seal the Book of Ruin. But at the end credits scene, the Book of Ruin was seen in the Southern Base which Reika Shindai is also a part of.
The Black Dragon & the White Dragon which crossed with Brave Dragon to form Emotional Dragon were part of this Book of Ruin. And recently during the Filming, Kamen Rider Saber was spotted fighting a Black colored Rider. If this Rider uses the Black Dragon from the Book of Ruin, could this mean that Southern Base is the next threat?