>>6686884he is saying that the person he replied to knows immediately that the character in the image is Jack the Ripper, despite the post nor even image file having no instance of that name at all, yet still claims to know nothing of the source material.
Of course this is ignoring the fact Fate/Apocrypha is currently running so one is VERY likely to have run into posts relating to that character elsewhere on this anime imageboard and learning the name that way.
>>6686810nah, that is indeed supposed to be Jack the Ripper. I enjoyed the idea behind the concept of her character when they first discussed the concept designs so many years ago, but then when they finally used the character in an actual work the outfit just had to be made loli bait.
Basically the background behind her being Jack the Ripper is that in that time period there were a lot of orphans in London. She was one that was abandoned by a prostitute and has a massive mommy complex, and went killing prostitutes looking for her mother.
I beleive this is just one of MANY possible Jack the Rippers in that franchise's universe though. People summon famous heroes from beyond time to fight in this Holy Grail war for them, and the heroes are influenced not only by who they actually were(in the universe) but also by various legends and tales. Since Jack the Ripper was an unknown person, there is the potential for more then just that girl to be Jack the Ripper.