Within a Hollow Heart - Chapter 177: Volume 2, : "The Abyss Beckons"

One day, a door to another dimension opened all over the world.

“Channel”

At the same time as the channel opens, different races appear on Earth, and mankind awakens its magical talent.

But…? Yoon Min-joon, was able to use magic long before the channel opened.

The forced escape of a reclusive loner who was once the only wizard on Earth.

“It’s dangerous outside the house.”

Beautiful doctor of Chinese medicine, Yu Gangan woke up from a coma one day to a cold, mysterious man. “Excuse me, you are…?”

A pair of profound eyes focused on her and replied, “Fang Zhihan, your husband.”

Did this man take her for a fool? He was obviously a fraud!

A little while down the track, he pulled her into his arms and whispered beside her ear, “Who am I?”

This time, Yu Gangan froze and replied, “Fang Zhihan, my husband.”

If he was a patient, then she was his sweetest medicine…

- Description from Novelupdates

Finding himself in an Last Airbender without an airbender around, a transmigrator waterbender goes on an adventure to stop the worst from happening to him.