Both productions are set in the same "universe" with Guan Hong Feng (ML in Day and Night) being a supporting/guest character in Reborn.

Lives of male leads in both productions get changed due to movies during the tumultuous period in communist China.

Both productions star Zhang Yi as ML who befriends a teenage girl he once had an enemy-like relationship with.

Similar premise - in Don't Touch Me, Your Majesty ML time travels and has to cross-dress as a concubine, while in Nobleman Ryu's Wedding ML has to cross-dress and become a stand-in for his sister. Both have extremely low budgets, but Don't Touch Me, Your Majesty is a parody, while Nobleman Ryu's Wedding is (slightly) more serious.

Both productions not only have Joseph Chang (Chang Hsiao Chuan) as ML, they are also quirky (with similar arthouse vibe to them) and bloody.

- Sunny Suwanmethanont is ML in both movies
- Both movies have a similar bittersweet vibe
- Both productions have unexpected endings

Both productions have a similar premise - Sunny is confused about his feelings towards two women. Dear Dakanda is the one with better writing and acting, so if you watched Stay: The Series, you should go and watch Dear Dakanda asap.

Both productions tell the story of undercover policemen and criminals trying to trick each other and prevail

Both are remakes of Cantonese movie "Infernal Affairs" - City of Damnation is an official remake, and The New World was only inspired by it - the plot doesn't follow the original script

Both movies were directed by Park Hoon Jung - while they don't share many similarities in plot, they have the same vibe

Male leads in both movies enter gangland as undercover cops and befriend their criminal co-workers. Both productions have a similar plot - unfortunately I cannot reveal more without spoiling either of these films. If you liked one of them, you'll likely enjoy the other one too

One of subplots is rather similar - "fake" (grand}sons taking care of their "fake" old (grand)mothers with Alzheimer's