Board Thread:Producer, illustrator,& music discussion/@comment-58.71.224.84-20170714023812/@comment-34277895-20180113120229

They're robots with Len being the male counterpart of Rin.

Or they're humans in a band with Kaito, Meiko, Miku, and Luka, were born at the same time, look and sound like genderswapped versions of each other, and even have the same surname b\c of theme naming, and thus are drawn with the same hair and eye colors.