The path to immortality through martial arts begins with being forced into marriage!

Cui Yi transmigrated, and into the body of a useless only son of a fallen immortal cultivation family.
At the beginning, all that's left in the family is a sister-in-law who hasn't married into the family yet and a child bride who's still immature and keeps saying she wants to have his baby.
Cui Yi thought this was a script with hellish difficulty, but then an ancient and mysterious nine-story pagoda suddenly lit up in his mind!
"The Nine-Layered Pagoda is the foundation of the Dao; with your longevity, you will illuminate the path of change!"
Others cultivate by relying on talent and resources, but Cui Yi cultivates immortality by spending his life!
It wasn't until Cui Yi discovered that slaying demonic beasts and wicked people could grant him more lifespan that he suddenly felt that the path of cultivation seemed to be getting wider and wider?
(The synopsis is inadequate; please come in, dear readers!)
(This book is also known as "How Can You Become Immortal If You're Made to Cultivate with Your Life on the Line?" and "Becoming Invincible from Being Forced into Marriage as a Child Bride")