The Story of Gumiho (2020)

Both series have that mysterious vibe. Also I see a similarity in the Grim Reapers and the Nine Tailed Foxes. The plot is crazy good in both stories. You should give it a go if you loved Tomorrow.

Both MLs are mythical beings who has spent centuries waiting for their true love who died tragically for them to reincarnate and return. When he finally finds her, she has no memories and a different personality.

ML is superman archetype, loner,
FL curious and brave despite childhood trauma
Both support justice in their own way , ML seemingly hesitant to get involved in worldly affairs
Dark but witty dialogue to create balance
Intriguing investigative adventure with romance at its core
****Please note these parallels are made after only two episodes -rest of episodes may alter this opinion.

Mythical-mystic things
Evil creatures
ML's brother wants to kill FL
Love story with reincarnation
Both of dramas have similar atmospheres

- Both dramas are about kind of destiny.
- In both dramas, we see ML looking for his love in different places over the years.
- The final one:In both dramas, the couple need some time together to find out what they have in common.

Eternal Love the main role is a white fox.
It's also known as Three Lives Three Worlds, Ten Miles of Peach Blossoms. It is based on the xianxia novel of the same name. Xianxia is a genre of Chinese fantasy influenced by Chinese mythology, Taoism, Buddhism, Chinese martial arts, traditional Chinese medicine, Chinese folk religion and other traditional Chinese elements (SOURCE: wikipedia)

The mythical nine-tailed fox, or gumiho, Lee Yeon had to settle in the city many centuries ago. Able to transform into human form, he eradicates supernatural beings that threaten the mortal world. His real aim is to find the reincarnation of his lost first love.
The talented television producer Nam Ji Ah works in a show that features urban myths. In the past, her parents were involved in a mysterious car accident and disappeared, and she suspects that Lee Yeon might be connected with this accident.
The half-brother to Lee Yeon is the captivating Lee Rang. Despite being half-human himself, he harbors a deep-seated contempt for all people. For sport, he will unleash his seductive prowess upon his human-du-jour, by promising to grant them their wishes, only to trick them into paying a hefty price for their earthly desires.
(Source: Lee Cox at MyDramaList)