|Box title = Erika Karisawa
|image = File:22528583209a4d4c1f40af5345f24e06.jpg
|caption = "A great man once said the world is a myth. I think he said it anyway. Even if he didn't I'm sure someone said something similar."
|Row 1 title = House
|Row 1 info = Ravenclaw
|Row 2 title = Year
|Row 2 info = Sixth
|Row 3 title = Gender
|Row 3 info = Female
|Row 4 title = Family
|Row 4 info = father (estraged), mother (awesome), Walker Yumasaki (brain twin), Kyohei Kadota (Dotachin), Saburo Togusa
Bubbling over with energy, Erika is a very strange individual. She has a rather warped idea about reality, believing that fiction and reality are both equally as valuable as the other and simply writing off the past as fiction as she sees fit. Erika comes off as charming despite being a tease, and is almost never seen without her partner in crime, Walker Yumasaki. Often than not it's completely impossible to tell their personalities apart as they both seem one and the same at times.
Of course, like most people there's a side to Erika that some don't know about. She's quite well-versed in novel-inspired torture, using manga as a reference on how to get someone to talk when they won't cough up the details. If Walker gets upset enough to snap at someone, it's her that calms him down, though these occurrences are rare in themselves. She can seem a bit teasing and sly, indicating she knows very well how to push people's buttons.
Although on the surface people only see Erika's otaku nature, the truth is that she's quite deep. Though she bases a lot of her thinking around occurrences in manga, Erika is capable of understanding real world happenings more than most. When Kaztano was kidnapped, she was the one who suggested he might have mistyped 'kidnapped', which no one paid attention to. She seems to be able to tell what the people around her are thinking, teasing them through nicknames such as 'Yumacchi' and 'Dotachin' which can be seen as forms of affection.
Born in Japan, Erika is an oriental halfbreed, her mother being of English background. When she was eight, her parents split up when her father found out her mother was a witch, and as a result she spends half the summer in Ikebukuro, Japan and the other half in her mother's hometown of Soho, England. It was during their split that she first discovered manga, finding it an easy escape from the harsh reality that had encompassed her life. She became engrossed in fantasy worlds, and it was during this time when she first met Walker, Kadota and Togusa while staying with her father in Ikebukuro.
Though she was able to distinguish reality from fantasy, sometimes it felt as though they blended. Days passed by without giving them a glance, and she discovered that Kadota and Togusa were wizards themselves, her seniors in her first year of Hogwarts, while Walker was her classmate and also spent half of his summer in Japan. It wasn't unusual to see the four of them together when class wasn't in session during her first year.
When Erika was in her fourth year, she started getting around with a wizard gang going by the name of the Blue Squares during the summers. Walker, Kadota and Togusa were also a part of this gang, which consisted mostly of muggleborns and halfbloods, but sometimes the rare pureblood as well. It wasn't long before things got out of hand, and the leader of their Yellow Scarves rivals had his girlfriend kidnapped as a bargaining chip. Erika and her friends defected and rescued her, but not before she had her legs cursed broken.
Things quieted down after that. The Blue Squares were all but erased, and Kadota's little gang continued roaming around Ikebukuro in Togusa's van. Erika stays with Walker for half of the summer before the both of them go back to her mother's before school starts. Their lives have been fairly normal since then, well as normal as otaku wizards can be anyway.