The term "yandere" refers to the disposition of characters who originally seem kind and gentle, but who prove to be frighteningly brutal in their devotion. Future Diary's berserk stalker Yuno Gasai, for example. Medicom Toy has distilled this defining charactistic for their premium Real Action Heroes line reproduction of the character.
The 30cm figure is staled to be released in first quarter 2013 for 20,790 yen ($265).
The anime and manga for comparison