She is a masochist, and has a high tolerance for pain. Iku is capable of training for hours on end, even going so far as to train all night long until school begins the next day. She's able to do over 101,000 times bat swings without collapsing, for better or for worse, though this may be due of her love of pain “I don't really know if this will get across just how thankful I am, but...thank you, Rentarou. I love you.”