Night Doctor (2021)

Night Doctor shares a lot of similarities with Code Blue.
- focus on young doctors forming a team under a supervisor doctor that work in a special system (Code Blue: Helicopter aiming to provide fast medical help in the field) (Night Doctors: doctors only working the night shifts to provide qualified medical aid during nighttime)
- the characters growing in their professions as well as personality
- struggles with obstacles
- friendship and team building
- similar characters and ambitions or insecurities
- good mix of comedy and drama

Code Blue is more graphic than Night Doctors when it comes to the medical scenes but not gory. Code Blue has 3 seasons plus spin-off, sequel, specials and a movie that are all connected story-wise. Here's the chronological order:
Code Blue Season 1 (2008)
Code Blue Special (Farewell Facing Tomorrow) (2009) (connects Season 1 and 2)
Code Blue Season 2 (2010)
Code Blue Season 3 (2017)
Code Blue: Another Everyday (Spin-Off) (2018)
Code Blue Mou Hitotsu No Senjou Special (2018) (Sequel and bridge to movie)
Code Blue: The Movie (2018)

Night Doctor is similar to Tokyo MER in that it too is a specially formed emergency care unit. They also go to emergency and accident sites, something the day duty doctors could never do. The program's advantage is that it eliminates the shift system, making it possible to provide appropriate care 24 hours a day. Additionally, their policy is no case is ever rejected -- they too have a leader with a similar conviction as Toyko MER's who believes that every life is worth saving regardless of the complexity of the medical case.

Both are heartwarming medical dramas focusing on the relationship between medical staff and the patient.