In the trailer for Kamen Rider Saber Episode 16, the mysterious man was seen holding a completely different Seiken Driver having Star marks in golden color. So Toei had announced that this Mysterious Man named Yuri is going to transform into Swordsman of Light → Kamen Rider Saikou (仮面ライダー最光). The word Saikou can be translated as Ultimate Light.
This Driver seems to have completely different Gimmicks. It seems like the Star mark plate can fold to reveal a golden band. Well his Rider form is not yet revealed, but we'll get to see the first look in the scans releasing soon in three to four days.