User blog comment:B214/Volume 21 info & spoilers/@comment-99.118.13.217-20160613135349

List of characters that should of "DIED" in Volume 21 (either heroic death, shocking/unforseen death, or sacrifice)

Saiji (tragic death out of nowhere, Sona holds his body and cries)

Kiba (dies protecting Rias as he is a knight of The House of Gremory)

Gasper (shows he's a true man and takes out entire Evil Dragon clone army)

Akeno (dies saving Issei from an attack from Apophis, because she can't loose him agian)

Cao Cao (bloody and badass death, he goes out swinging and takes a lot of enemies with him)

Sirzechs (sacrificed to permanantly seal Trihexa)

Azazel (sacrificed to permanantly seal Trihexa)

Michael (sacrificed to permanantly seal Trihexa)

Odin (sacrificed to permanantly seal Trihexa)

Zeus (sacrificed to permanantly seal Trihexa)

Brahma (sacrificed to permanantly seal Trihexa)

Ophis (gives up her life to cure Issei's condition so he can love boobs again and go into DxD mode once more so he can kill Apophis)