It means superpower, and it's Inou, no kongou.
I forgot the black haired girl's name, but here's what she says starting on page 7:
A representative battle/match... The star of the inter-school battles!
My sisters have both been selected as representatives, leading their team to victory! (gotta use context clues, remember she's part of some clan or something)
I wanted to take part because I entered a highschool for superpowered people my heart yearned for!
You can't just MTL sentences like these because of the way they're constructed.