Recommendations

Both have two people ending up living together because of a situation and ending up falling in love with one another.

Maybe the tone (hana no kusari is darker) and the genre are different, but the main point/ main twist is quite similar ....
You will understand it if you watch
XD

Although sword of legends is in Chinese, both dramas have the same historical/fantasy setting and the two leads and stories are similar in many ways.

Similar themes and characters: both teachers have a "secret identity" and help their students solve their personal problems.

While watching Office (2015) it sort of reminded me of the breathtaking "Confessions" because the cinematography of the two films are quite similar in nature though the plots are absolutely different. If you are into thrillers, this movie is the right one for you to try next.

another of those typical movies with a lot of violence and gun shots.. altough this one has a lot more violence and is only for 18+ viewers

Both deal with mental health issues. Other than that they are different but I get a similar feeling from both.

Two best friends start living together and realizes their feelings for each other.

Somehow the dynamic between the couple reminded me of this drama. Problems between a married couple, though one of them additionally features a child.

Same idea of trying to help a class of troublesome students, a life-changing school experience, array of characters and so on. Strongly recommend.

Same idea of a class of troublesome students, and an optimistic person (in gokusen a teacher, and asuko march the only female student) who help turn everyone's lives around. Scheme of the episodes it similar, that it goes through various characters and shows the efforts of protagonist and their kind hearts that bring resolution to the issue.

It kind of follows the plot of 'rich man with poor girl' although The Heir follows more of a romance high school route, whereas Scent of a Woman follows a more serious, medical route, but still with some romance involved.

I think they are the same story with some changes the japanese version was very good and fun to watch

Both dramas are action dramas about the police. The difference between the two is that in Athena: Goddess of War, it's talking about secret agents while Poseidon is about the police.