I Kept Pressing the 100-Million-Year Button and Came Out on Top, Vol. 9 (Light Novel)

A traitorous Holy Blade and a former member of the Four Imperial Knights launch an attack to steal the Billion-Year Sakura--an eidolon--forcing Allen and his friends to face their toughest opponents yet. How will they manage to stand against the true power of a Soul Attire...?!