i don't think Dianthus is a male. There was a user in the Ticket Gacha Thread calling Dianthus "his" and not "her"...
moarsi joked about that pointing out he had known Dianthus is a Trap
http://harem-battle.club/flower-knig...y-daisy-5.html (Page 5, Post 45 and 46)
About the "Japanese Speaking" i can't say anything cause i don't know how to speak Japanese
But her Hentai-Scene implies that she is 100 % a Girl. I couldn't see a dick or something similar.
To be fair i would scream if my Favourite Girl right now is a Guy
A Phrase from her Hentai-Scene:
"Dianthus's tight pussy gripped my cock hard"
So i don't think she is a male...