The Heroic Legend of Alain - Season 1
1 - Chapter 1
Air Date: April 13, 2016
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.
2 - Chapter 2
Air Date: July 13, 2016
Continuity with Kamen Rider Ghost: Chapter 2 occurs over the course from episodes 16 to 26.
3 - Chapter 3
Air Date: October 5, 2016
Continuity with Kamen Rider Ghost: Chapter 3 occurs sometime during and after Episode 29.
4 - Last Chapter
Air Date: January 11, 2017
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".