Recommendations

Both series have flashbacks from the past and a range of mysteries, which involve multiple characters and someone's death.

Both mature themes and content for older audiences with a good balance of romance and comedy. Really relatable and slice of life with great casting.
Twenty is more focused on the bromance between the best friends than their individual romances whereas My P.S. Lover is about the main characters development but still shows their respective friendship circles and their own friendships are still portrayed with good chemistry.
Really enjoyed both!!!

Its pretty similar...
1. the two girls and tough yet fragile
2. the guys are the hard to get ones.
3. both have drama and romance in the air

Both dramas are about unconventional heroes trying to save the people from a corrupted king, so many twists and turns, keep you guessing what will happen next.

Though not the main focus of this drama, the female lead went through similar experiences and developed the same way before meeting the male lead who helps them become happy. Both have a good look on life and development.

The female lead has a similarly cold and distant personality before meeting the male lead, who helps her open up and overcome her fears in relationships.

both present the situation of an extremely capable woman in times women had little to no perspectives on getting an education and using it for the common good. They aren't greedy for power, but want it to save the state or improve the quality of ordinary people's lives. Their idealism comes in pair with an acute political sense. Even though they're surrounded by the men who love and admire them, their advice is often disregarded, their possibilities limited and their lovers would gladly just put them in a cage so they wouldn't get hurt. You got your fun, girl, now go home and let the boys play.
Both are gender-benders (short arc in Empress Ki, more in Tempest) and hide their identity. Both have multiple love interests. Both become a ruler's concubine. Empress Ki has stronger rivalry in the harem, while in Tempest even though the harem is a scene of a financial schemes, women are in comradery.

both shows are about the afterlife and what these characters did in their past cause them to be who they are now.
both leads are handsome as hell!
both dramas have ghosts in them.

The male leads give off the same vibe. Lie to Me the male lead is a bit more stiff. The female leads are somewhat similar. Also the second male leads are similar. My Secret Romance is like a more light hearted version.

Same theme ..a young guy getting accused of a crime he didn't commit ...fabricated city is more action ..new trail is more emotional .

One is a Korean movie and the other a Thai drama, but both have a hitman who falls in love with an innocent woman who's an artist. (And both are awesome.)

Its also a mermaid story. Bt much bettr than " the mermaid". The only thing is its a Korean drama

Both series portray real people and real stories. It's a fresh and genuine perspective on the lives of gay men.

Both dramas involves two non-relatives twin women (rich woman and other is poor from each drama), of which the rich woman from each drama engaged to the son form rich family but for business purpose and not real love but later on due to different reasons the poor one forced to be married to those chaebol sons and replaced the rich ones. In bride of century JYK didn't want to be married by CKJ so NDR replaced her. In mask, due to the coma happened to SEH and killed by her in-law, she was replaced by BJS. Both those sons from each drama had no feelings to these poor women in first place but falling for them later.

both are about a forbidden love story between a man and a married woman.. both have r rated scenes