Gekkou

A Second-Year at Gessen Girls' Academy, Gekkou is a cheerful, energetic and positive girl that is greatly admired by the students of Gessen Academy. Though they are often mistaken for twins, Senkou is in fact Gekkou's half-sister, a result of a single father and two mothers.

In contrast to her sister, Gekkou is very out-going and likes to make friends. She was notably the first one to approach Fubuki and befriend her, and most of the time likes to drag Sekkou into whatever schemes she has whipped up at the moment, much to her sister's dismay.

In the anime, Gekkou is a Middle-Schooler who was only pretending to be nice for the sake of overturning the shinobi world. I don't know why they changed this, because in the mobile game New Link, she is a High Schooler and benevolent instead. It's almost like they wanted to manufacture conflict to service a plot that was dumb anyway.

Also, she's a member of the Student Council.