Regarding her nickname “Nanjolno” it was given to her by her friend Haruka Hitomi from the same Agency.
It was apparently a combination of “Ojou” (Young Lady / お嬢) + Nan (from her last name / 南) = Nanjolno.
They kept on hearing Haruka Hitomi use it and the others got interested in it and used it as well from then on.
With the said friend, she often refers to her as Hitton (ひっとん) while Haruka Hitomi calls her Nanjolno or Jolno.
Her nickname “Ojou” came from the Da Capo II Radio named “Radio Da Capo Hatsunejima Diary” (ラジオ ダ・カーポII 〜初音島日記〜) which she hosted with Asanuma Shintaro in 2008, he gave her this nickname.