The Female Lead of IOTNBO has such a "female empowerment" and "psychotic" vibe with cranky, antisocial like exterior and yet deep inside has a softer interior of wanting warmth and answers to her life. Just like how Jang Man Wol were in HDL. If I were to quote I saw from an article, "Ko Moon Young is like the mature version of Jang Man Wol, much more crazier and overbearing"

If you like the cameo that Kim Soo Hyun did for Hotel Blue Moon, then I can almost feel as if his character in IOTNBO is like the prequel of Hotel Blue Moon before he actually became a hotel owner. It is as if the reason for him to own this hotel of ghost was so that he could looked for his FL. In this drama, he still has that cool exterior but is much more warmer inside.

The story writing has similar theme of trying to resolves worries/regrets of people, such as in HDL, they resolve the ghost's regrets for them to ascend to the afterlife whilst in IOTNBO, they give treatment to the patients so that they can heal back to normal and our Male Leads for both drama wants to embrace and heal the scars of our Female Leads.