Talk:Toaru Majutsu no Index SS: Stiyl/@comment-36841586-20180906204541/@comment-38963557-20190513142234

To begin, Richard Brave is arrested in this story, which means it takes place after Kanzaki SS, where he is still working on his master plan. That volume mentions that she fought an angel before, thus taking place after Angel Fall.

Stiyl SS also shows that Komoe-sensei has already been introduced to Stiyl, which means that this takes place after the Daihasei arc.

Most important of all however, Kanzaki SS also mentioned that the rising tensions between Magic and Science conflict influenced a steel manufacturing plant in Denmark to being overworked with orders.

Thus, we can reasonably conclude that this takes place after the 9/30 incident, but before the English Civil War. That narrows down the timeline to approx. 2 weeks or so.