Event ideas I just came up with:

—HaroHapi at the amusement park, carnival-themed costumes
—Hina/Sayo twin switcheroo (they’ve already had a few events, but this would be too fun)
—PasuPare at a rock concert, pastel goth costumes
—Non-vocalists do karaoke
—Movie/video game night
—Superhero event with the girls designing costumes for a new song (potential for My Hero Academia cover)
—Magical girl event (since PasuPare already has magical girl-like costumes, this would be best for another band)
—Helping at an animal shelter (with Yukina possibly adopting a cat)
—Girls’ night out with Lisa giving makeovers and going shopping
—Guitarist event where Yukina decides she wants to play guitar like Kasumi and Ran, but doesn’t know how to tell Sayo

These are just a few ideas. Let me know if you have any more!