I'm going have Y/N to become Kamen Rider Saber as it is more fantasy than others kamen rider.
Kamen Rider Saber Basic Form
Kamen Rider Saber Dragon Eagle Form
Kamen Rider Saber Saiyuu Dragon Form
Kamen Rider Saber Crimson Dragon
Kamen Rider Saber Dragonic Knight Form
Kamen Rider Saber Primitive Dragon Form
Kamen Rider Saber Elemental Primitive Dragon Form
Kamen Rider Saber Final Form Xross Saber
Kamen Rider Saber Almighty Saber Form
Of Course I will add Kamen Rider Blades and Kamen Rider Espada as his allies.