When they're not going at school so do Jonu and Mirai use the time they have together to play around. And this time so did Mirai get a costume made Spider-Woman costume made by Heart (not shown in the picture). So yeah, the picture explains it. Let's just hope that they don't break anything.
Yes, one of the ways Mirai uses to learn english is to read comic books, and has become a fan of Spider-Woman (the Gwen Stacy version). I haven't read any of her comics yet (I do like the costume though), but I can assure you that I will get to reading them soon.

(That frame on the drawer shows their parents that still lives in Japan. And sorry to dissapoint you, but her bags in her kimono are actual bags where she stores about anything she could ever need in. No idea why she wears her bags like that.)

Jonu and Mirai (c) Cyborg-Lucario