In the time since PoDD, some things have changed. Yumemi Okazaki has successfully set up a small academy for studying the interactions of technology and magic, where she, her former assistant Chiyuri, and new apprentice Rikako, teach. Since then, they've rebuilt the Dimensional Hypervessel into a newer model, the Dimensional Cannon, drawing power from the Underground Nuclear Reactor. Using this, Chiyuri returned to the outside world and has since gotten her doctorate, and Rikako was able to become the first native Gensokyan to get a college degree.
Chiyuri's outfit has changed the most, having abandoned the old sailor outfit for a hoodie and skirt, though she kept the hat. Yumemi's given up her cape, in exchange for being able to wear her wing-pack more easily. Rikako's just opened up her coat, that's all.