Both are about the main male lead time travelling. In Tunnel he goes to the future via a tunnel whilst in NNTTT he goes to the past via incense sticks. They both have to solve murder(s) whilst time travelling. A difference is that in NNTTT, the male lead can travel back and forth but only for a maximum of 30mins whilst in Tunnel he is stuck in the future and has to find a way back.
They are both about the love for music with elements of a school setting. Also the female falls in love with the male first in both dramas.
Both have similar vibes with the storyline of Ji Sung is trying to find justice for his lost lover/wife. Both are fantastic and if you like one you would like the other.
Both dramas are about making food whilst a romance blossoms between them.
Each drama has different storylines but they have a similar vibe to each other. They are both very funny and the main male lead in both dramas is Jo Jung Suk.
Both dramas are about reconnecting with the ex years after they break up and solving the problem that caused them to break up in the first place. My Sunshine is more sombre whilst My Best Ex-Boyfriend is more comedy.
They are both crime dramas with a past connection between the male lead and the female lead. Throughout the drama, the crimes they solve lead to a bigger picture which shows their past connection. Also a romance develops between them in both dramas.
They are both about best friends falling in love. In ILULULI (taiwan drama) they already live with each other whilst in 9E2O (korean drama) they come to live together later in the drama. Both the male leads have another love interest as well.
They are both student-teacher relationship. Hello Mr. Right is a Chinese drama whilst Close Range Love is a Japanese movie.
Similar storyline were the main female lead is involved with the death of main male leads girlfriend thus creating a love/hate relationship between them. Secret is Korean whilst Kleun Cheewit is Thai.