This follows Rooftop Sword Master.
The last panel of each chapter with the words "Irregular Squad" on top of the silhouettes of 6 people refers to the universe that the stories belong to. We're at the 2nd silhouette right now, 4 more to go.
I get that being non-linear with your storytelling is more engaging, but when you can't tell what's happening when on either end, and none of the names or events make sense, you REALLY ought to go in order and explain what the hell is happening.