(edited by Orochi Nightmare)
I have to say Maki Genryusai from Final Fight 2, Capcom VS SNK 2 and the portable versions of Street Fighter Alpha 3 is the greatest underrated Kunoichi heroine and my 2nd favorite fictional Kunoichi heroine character although her appearance doesn't seem original obviously since she looks like Daisy from Dragon Warrior: Legend Of The Hero Abel 1989-1991 anime series with Leona Heidern's hairstyle but blonde and slightly longer cosplaying as Mai Shiranui and her personality seems a little bit similar to both Daisy from Dragon Warrior: Legend Of The Hero Abel and Revy/Rebecca Lee from Black Lagoon Manga and Anime series with the same wicked smile but I still prefer her over Mai although I liked her too.
For some reason Kasumi Todo as in her NESTS Chronicles Saga version reminds me a lot of Kamiya Kaoru from the infamous anime and Manga series Rurouni Kenshin.
That's would make sense that Kasumi is modeled after Kaoru but SNK Playmore didn't mentioned it to avoid being sued.
10 Votes in Poll
It looks like this art of KOF'99 heroines is made by the same artist as all three Fatal Fury animated movies. It looks very similar and amazing too. My favorite heroines in the game including Athena, Kasumi, King, Leona, Mai, Mary, Xiangfei and Yuri look great.