Unstable Castle of Tokarev by Kagura Uguisu and Toshihiko Tsukiji — Completed

Also known as Tokarev no Ayaui Shiro

Untitled

Ayaka has a dear friend named Hiroko. Hiroko suddenly vanishes from Ayaka’s life, saying that she must save someone important to her. Since that time, Ayaka hasn’t heard anything from Hiroko, until a girl’s corpse is washed up on shore, and she’s holding a letter from Hiroko which reads: “Come save me.” Ayaka sets off to save her best friend, and ends up in a mysterious school where everything seems too good to be true. Is it?

Volume 1
Chapter 1 released Feb 19 '10
Chapter 2 released Jun 21 '10
Chapter 3 released Sep 4 '12
Chapter 4 released Nov 18 '12
Volume 2
Chapter 5 released Dec 23 '12
Chapter 5.1: Spinoff released Jan 22 '13
Chapter 6 released Mar 14 '13
Chapter 7 released Apr 30 '13
Chapter 8 released Jun 5 '13