They legit didn't have a black guy in the shinsengumi tho. There is no reason to add him. What would you think if they made Marthin Luther white in this manga?
@DaCup Using Martin Luther king as an example is a very shallow one. The character you're comparing him to will probably have zero dialogue what so ever so him being dark skinned will most definitely have no impact in the story whatsoever because at the end of the day, the main people fighting are japanese. You shouldnt be bothered or even care so much. It's probably like a small reference to Yasuke or something. Plus the person who is writing the plot is probably Japanese and if they aren't offended then let them run with it