Both are wacky dramas with chaotic female leads dealing with ghosts and the supernatural. Youkai Sharehouse is more funny while Tenma san ga Yuku is more scary.

Similar story of male lead who's never been in a relationship finally get into one and discovers it's not all fun and games.

Both are wacky dramas about a chaotic female lead having a "Eureka" moments every time they got a clue or solve a case.

Similar wacky drama about a chaotic student who loves solving crimes while agitating her senior and detectives involved in the cases.

Similar relationship chemistry and drama vibes of two leads trying to protect each other from time to time, often clashing with each other over what works for them.

Similar shenanigans of the seemingly cold male leads (bodyguard/cop) trying to protect the funny female leads being targeted by her enemies.

Both are lighthearted dramas about a girl living with someone unexpected.

Iine! Hikaru Genji-kun is about a girl living with someone from Japanese historical literature.
Youkai Sharehouse is about a girl living with monsters from Japanese folktales.

Good shows if you're interested in comedy and Japanese culture.

Both are cute comedy dramas about the main lead living with someone unexpected.

Kanojo ga Joubutsu Dekinai Riyuu is about a guy living with a ghost.
Iine! Hikaru Genji-kun is about a girl living with a guy from the past.

Both leads try to send them to their destinations where they belong but only to fall for them.

Both are cute dramas about a human living with a spirit.

Kanojo ga Joubutsu Dekinai Riyuu is about a guy living with a Yurei (Ghost).
Youkai Sharehouse is about a girl living with Youkai (Monsters).

They're both about how the complex relationships change them all for the better.

Both dramas are about a guy who discovers a ghost living in the house he just moved into and how the ghost influence his decisions that affects his career.

Although Kanojo ga Joubutsu Dekinai Riyuu is more wholesome, Kasuka na Kanojo is more serious as it focus more on the struggles of being a teacher.

Both are cute and wholesome shows about someone who moves into a new house to start a new life when he discovers a ghost living in it.

Similar tale of a female android / cyborg saving the human male in times of despair.

While Cutie Honey is more of a cyberpunk genre of the guy looking up to her as a hero in a dystopian future, Cyborg She is more of a romantic relationship between a human and a cyborg in the present day.