Responses
No, the 'author' writes the story (or sometimes novel which the manga originates from), and the 'mangaka' draws a manga based on the story - sometimes 'mangaka' and 'author' are the same, for they write their own stories.
So it's rather an administrative issue to add the category 'mangaka' between 'author' and 'genre'.
Is Gothou Shinobu (this manga author) & Kannagi satoru (from this manga: http://www.mangago.zone/read-manga/only_the_ring_finger_knows/ ) is the same person? I'm really curious because their arts looks similar.. ( ̄へ ̄)