The Heroic Legend of Alain

Episodes

E1
Chapter 1
Continuity with Kamen Rider Ghost: Chapter 1 takes place in 1950 (65 years before Ghost), 1960 (55 years before Ghost), 2005 (10 years before Ghost) and 2015. As for 2015, this chapter occurs over the course from episodes 1 to 12.
E2
Chapter 2
Continuity with Kamen Rider Ghost: Chapter 2 occurs over the course from episodes 16 to 26.
E3
Chapter 3
Continuity with Kamen Rider Ghost: Chapter 3 occurs sometime during and after Episode 29.
E4
Last Chapter
Continuity with Kamen Rider Ghost: This chapter takes place sometime after series finale. The final scene takes place many years into the future, presumably sometime after "Kamen Rider Ghost RE:BIRTH: Kamen Rider Specter".