Both set during the Japanese occupation of China and the espionage/collaboration against/with the Japanese, Best Enemy was FAR more suspenseful in the plot and script to compel you to keep watching because it's not clear who is the 'good' guy at every turn.... find it at iQiyi but look up the lead's name as the title is not listed in English but it is there and has subtitles.
Two male leads with strong bond. Fighting and action for life and death with ancient background. Betrayal and yet protecting each other. Many leads are getting killed. Relating to Military or police background.
Both dramas are set during the Japanese occupation.
Both dramas tell the story of good friends who become enemies due to different backgrounds.
Both male leads work under the Japanese government as undercovers.
Both male leads have multiple identity.
In both dramas, first and second male lead have the same love interest.