This blog serves to show the chronological order of events in this series. This includes short stories, Slash/Dog, the Great War, the Devil Civil War, EX/IX, and character's pasts. From the top to the bottom is the order.

V = Volume

Pre-Great War

Great War

Post-Great War

Devil Civil War

Tepes and Carmilla Faction Are Formed

World War 2 - Kokabiel Fights Strada

Assasination of Yaegaki and Cleria

V15 Scarlet and Crimson

Koneko's and Kuroka's Past

V15 May the Shine be on You

Gasper's Past

Dulio's Past

Vali's Past

DX.3 Cross×Crisis

High School DxD Universe -SLASHDØG- 1

High School DxD Universe -SLASHDØG- 2

V1 Devil of the Old School Building

V8 Devil's Job

V2 Phoenix of the Battle School

V8 Familiar's Requirement

V3 Excalibur of the Moonlit Schoolyard

V8 Memories of Breasts

V4 Vampire of the Suspended Classroom

V8 The Breasts of Tennis

V8 Hell Teacher Azazel

V5 Hellcat of the Underworld Training Camp

V8 300 Issei

V13 A Special Filming Devil

V13 Issei SOS

V6 Holy Behind the Gymnasium

Having a Mad Tea Party!

V7 Ragnarok After School

V13 The Disturbance of a Devil

V15 Holy☆Maiden Goes to the Holy-Land

DX.1 Abduction ERO!

DX.1 Stop! Yuuto!

V8 The Fun Gremory Family

V13 The Unresurrected Phoenix

V13 Armageddon at Sports Day!

V15 Magical Girl Ria☆ For Real!?

DX.1 Ultimate!! Big Brother Mask

V9 Pandemonium at the School Trip

DX.1 Records of Breast Dragon Emperor’s Pleasure Adventure

DX.2 A Large Chest is the Sun

DX.2 The Student Council’s Decision

V10 Lion Heart of the School Festival

V15 Let’s Go with Training! ~Hell Chapter~

DX.2 Let's Go with Training

V11 Ouroboros and Promotion Tests

V12 Heroes of Tutoring

V12.5 My First Errand

V15 Wolf's Emblem

25 (Twenty Five) at the Clubroom with Rias-Club President

Rias in Wonderland

V13 The Worries of the Next-Next Heir

DX.1 Love Song to the Reincarnated Angel

DX.1 Let's Go to Onsen

DX.2 Worship☆Dragon-God Girl

DX.3 Asia's Treasure

V14 Wizards of Career Counselling Chapters 1-6 Pt 1

DX.2 Forked Cat☆Ninja Scroll

V14 Wizards of Career Counselling Chapter 6 Pt 2-Chapter 9

DX.3 The Ordinary Days of Red Dragon Emperor

V15 Episode Issei.1

V15 Episode Issei.2

V15 Episode Issei.3

V15 Episode Issei.4

V15 Episode Issei.5

V15 Episode Azazel.1

V15 Episode Azazel.2

V15 Episode Yuuto.1

V15 Episode Yuuto.2

V16 Daywalker of the Extracurricular Lesson

DX.3 Let's Go with Training! ~Mascot Chapter~

V17 Valkyrie of the Teacher Training

DX.2 Maniac's Sanctuary

EX

V18 Funny Angel of the Christmas Day

V19 Durandal of the General Election Chapters 1-4

DX.1 Phoenix of the Battle School Building DX?

DX.3 Talents of the Student Council

DX.3 Worldly Desire of Steel

V19 Durandal of the General Election Chapters 6-7

DX.2 Night Parade of One Hundred Demons and Pandemonium

V20 Belial of Career Consultation

V21 Lucifer of the Optional Attendance

V22 Gremory of the Graduation Ceremony Chapters 1-4

DX.3 Graduation Trip and Vortex Bunch

V22 Gremory of the Graduation Ceremony Chapters 5-10

V23 Joker of the Ball Game

DX.4 (V23.5) Student Council and Leviathan

V24 Grim Reaper of the Off-campus Learning

V25 Yggdrasil of the Summer Courses