Both dramas have a different theme each episode within a different setting that includes the main character.
Kishibe Rohan wa Ugokanai is more of a science-fiction drama while Takeuchi Ryoma no Satsukyu is more of a slice of life drama, however I found it interesting that both dramas included episodes in which each could be pursued as a drama / movie.
Shares the same themes of Japanese spirits and ghost stories. Both Kishibe Rohan and Watanuki Kimihiro have a supernatural ability that helps them with the spirit world
Both have creepy horror vibes, but fun to watch.
Unpredictable plots.
Leads with special powers.
The romance is not fluffy at all.
(both plots are the kind only Jdramas can provide really)
Both are from the same manga. Although Kishibe Rohan is a character from the manga, he didn't appear in the movie and is kind of detached from the manga world in the mini drama adaptation.