Houkai Gakuen EX is a special comic introduced in version 2.3 of miHoYo's online game, Houkai Gakuen 2. The story also comes with her own MAD version.
The story set in Middle age, when black death known as honkai pandemic haunt entire europe. The Schicksal using honkai box to purify outbreak causing the victim turned into honkai beast. Kallen Kaslana decided to steal honkai box and destroyed it but instead she got shot by bullet and stranded upon in land of yamato(known as Japan) in Yae village. After that she was saved by guardian miko in that village named Sakura. This is fateful story between two girls.

(Houkai Gakuen 2 timeline: version 2.3 as World Boss and 4.0 as Limited time Coop Mode)
(Honkai Impact 3 estimated timeline : Direct Sequel of #Book 1009 and Half Century before #Book 1001)

Main Story :
# Book 1001 = Escape From The Sky
# Book 1002 = Cherry Blossom Recall
# Book 1003 = Mystery of Stigmata
# Book 1006 = Anti-Enthrophy Invasion
# Book 1007 = Gratitude Arc
# Book 1008 = Moon Shadow

Side Story :
# Book 1004 = Violet Sea Tales
# Book 1005 = Dark Sakura Tales | Guns Girl SchoolDayZ EX - Sakura Arc
# Book 1009 = Purple Kite's Tales
# Book 1010 = Secret of the God Keys
# Book 1012 = 2nd Herrscher/Lawman

Spin-off :
# Book 1011 = When Kiana Play Honkai Impact
# Book 1013 = Valkyries' Dining Escapades
# Book 1014 = Summer Memories