[quote=@Demon Shinobi]
<Snipped quote by Raijinslayer>

Obviously the only yandere-Cynthia should be modeled after Yuno Gasai. 
And i never watched School Days. Just know the ending as well.
[/quote]

The fact Cynthia can actually make the room dark, or even pitch black, would make her a cery svary Yandere indeed. Also, if Cynthia went Yuno, that hotspring would've been filled with blood by now.