Both relationships begin with a friends with benefits style situation. Both have parties that are reluctant to get into a real relationship due to varied reasons. Similar level of intimate scenes.

ML and FL have a similar relationship. ML is smart while FL is dumb. Same plot as Itazura na Kiss, Kiss me

ML and FL very similar relationship. FL loves ML, ML is very aloof and they often fight. ML is super smart while FL is a bit dumb. Same plot as Playful kiss, Kiss me, Itazura na Kiss.

Kiss Me has a similar vibes between the ML and FL. They show attraction and yet also argue and disagree often throughout the show. Both have a dumb FL and a super smart ML.

Similar elements of showing social class struggles, the desperation of lower social classes trying to climb out of poverty and almost impossibility of them escaping poverty entirely.

Similar plot where main character is in a sort of limbo where they have insight into the enemy.
They use their human and more monstrous side together.

Some of the same main cast members.
Post post apocalyptic life with humanoid monsters.
Human vs monsters

Both have to do with human transformed monsters.
Conflict on interest on whether all are fully monsters or not

Both dramas portray the Tsundere vibe, stand offish but also shows affection to their lover. They also both have aspects of school and work.

Both explore how evil spirits and evil within oneself can lead to humans attacking each other.
Uncanny Counter is a bit more light and cartoonish in delivery while Hellbound is set up more like a dystopian alternate universe.

Both shows explore the minds and actions of people. Exploring the question of what is truly good and bad and what humanity is out of these two are very deep in both shows. I think an important factor in both shows is the initial desperation for money, which in that point in time equates to survival.
The filming and vibes of both shows make it hard for the audience to tell if a scene actually happened or if it was simply a hallucination/imaginary.
I don't want to spoil the show so I can't say much more but if you like one of these you will like the other.

Unfortunately this recommendation is a spoiler.

Same messages about learning to love life and find those who care about you through a game administered by death its self.