Daidouji

A former(?) student of Hanzo National Academy and legendary shinobi, Daidouji is someone who has an exceedingly single-minded view on life. She desires to become stronger and to fight strong people, anything else is simply secondary in her pursuit of power.

Once the longest reigning student in Hanzo Academy's history, Daidouji now spends all of her free time training and looking for powerful opponents. It's heavily implied she lives somewhere in the woods, uprooting trees, fighting large animals and hunting food with her bare hands.

She has a longstanding, mostly one-sided rivalry with Rin and yearns to defeat her one day. Her training can be largely centered on her efforts to defeat Rin in battle, but the woman always managed to defeat her time and time again. To Daidouji, Rin is her greatest roadblock in her path to become the ultimate warrior.

She is the physically strongest character in the series, able to uproot trees, lift busses and shake the very ground with ease on her part. She's also shown to be a little dim-witted, as she often charges into battle without thinking and can't solve basic math problems.