Juuken Sentai Gekiranger (2007)

Both have dark themes
Both are about martial arts
Both have red ranger dad that turned to the dark side
Both have ancient feud clans
Both have Chinese aesthetic

Both Dairanger and Gekiranger are heavily Chinese-inspired seasons of Super Sentai that are also martial arts heavy. Dairanger even has an ambiguously "Chinese" Pink Ranger and Gekiranger's movie is set in China.

They each also only have a single girl on the team (although Gekiranger does at least have other females in support roles) and both have an episode that make use of an actor's real life twin.

It's the 30th sequel of the series from Super Sentai right after GoGo Sentai Boukenger which is the 29th sequel. If you would like to watch the super sentai series chronologically.

It's the 31th sequel of the series from Super Sentai right after Juuken Sentai Gekiranger which is the 30th sequel. If you would like to watch the super sentai series chronologically.

Both star main characters that grew up in the jungle. While gekiranger takes a more light hearted approach to that both do show the main characters having to adjust

It's the very first Super Sentai series what made many of it's successors possible. If you want to watch the original first season of the Super Sentai series.