Given that mapping an anime/manga-style drawing onto real life appearance is at best a loose "adaptation" and at worst a matter of "eye of the beholder", Mikuru and Kurumi can both "look just like" source!Mikuru very easily. There's no reason to posit some difference in their appearances.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.