plain-dude:

More details have been released for the new novel for Shingeki no Kyojin, “LOST GIRLS”, written by Seko Koji. It will be a collection of three stories, consisting of Mikasa and Annie’s Visual Novels, and an additional extra side story specially penned by Seko Koji. Here’s a preview for the stories.

Lost in the cruel world
“You better hurry up, or you won’t be able to meet Eren again”. Mikasa looked at the face of the man in the mirror. However, what is reflected, is her own distorted face. Mikasa gathered her breath, and asked timidly, “Who are you, uncle?”

Wall Sina, Goodbye
(not translating the preview for this because it’s hard. Have a link to the summary instead)

Lost Girls *new story*
The sunlight grows fainter as the sunset becomes more pronounced outside the window. A quiet wind blows, and the leaves rustle. “Annie, what is that burden you’re carrying?” Annie takes a look at Mikasa, and shrugs her shoulders.

Comment from Isayama Hajime
“Reading this book will allow you to understand the primary reason Mr. Seto managed to turn the anime into such an amazing production.”

Comment from Seko Koji, also scriptwriter for Snk anime
“There is a reason why this story revolves around Mikasa and Annie (both quiet girls), but it will take forever to explain it, so I shall spare you the details. As someone who was involved in the production for "Shingeki no Kyojin”, I was, in a word, helplessly charmed by the burdens held by Mikasa and Annie, and at the same time, I wish to understand them even more as I write about the burdens they carry.“

Note: "Lost in the cruel world” and “Wall Sina, Goodbye”, was released along with the Anime Blu-Ray Vol. 3 and Vol. 6 respectively.