The Story of Kyrie is a side story from the Umineko: When They Cry series highlighting the backstory of Kyrie, as well as a new short story about her. This is where the minor character Karin makes her debut.
The story highlights a lot more of Kyrie's backstory more than the original games did. It talks about her life in the Sumadera family, and her struggles being the next head, as well as her reasoning for leaving it all to Sumire. This is also the only story to be from Kyrie's point of view the entire time.
Karin is a new character created by Blushii in order to fight Kyrie. Karin likes to taunt Kyrie, despite being the other side of the same coin of her. Kyrie is both bothered and amused by her presence, and the two have a complicated relationship. Blushii is the only one who knows Karin was made as a haphazard joke.