Hotel del Luna

Both are high fantasy genre Korean dramas written by Hong Sisters. Hotel Del Luna is modern, AoS is historical fantasy. FLs are used to be assassins before.

the actors look very similar lol. you should definitely give hotel del luna a watch. there are small resemblances here and there.

both have "things not everyone can see" vibe going on, as in the hotel with the ghosts for Hotel Del Luna and the realization of the life outside the comic in Extraordinary You
the link to the past ("past" in EY case being previous story)

and similar ending

Both are set in a hotel.
Both have a scene of mystery and suspense.
(SPOILER) Both have a romance that slowly blossoms over time.

recommendations are not just about similarities, so I'll just say (beside be melodramatic) TTON is the drama that got me out of my HDL slump~

In the heart of Seoul stands a mysterious, ancient hotel, managed by the greedy and resentful Jang Man Wol, who has spent a thousand years running it. Bound by a deity to prevent her from self-destructing due to her anger and thirst for revenge, Man Wol’s only chance of freedom lies in letting go of her hatred and finding love. Her eternal curse forces her to serve the bizarre clientele of the hotel. When Goo Chan Sung, a former hotel assistant manager, is forced to take over due to a deal made by his father, he helps manage the hotel’s finances, possibly offering the key to Man Wol’s redemption.

Mistura de romance, fantasia e espíritos. Protagonistas ligados por uma missão do além e sentimentos eternos.