Yumiko was still thinking of how he killed his other family member just a few days ago. Anger fueled him. He even went into Undersea to train. Which might even be illegal. But he didn't care, at least for the moment. He threw kunai down at certain points on the walls. Most stuck deep.
Once he ran out of kunai, he then began air boxing. Thinking of his father, who he also killed. Imagining if he could have done worse. He hated who he was. He felt like a burden to these people, to always be watchful of their own backs, just because they have heard that he killed two of his family members. And that's what really pissed him off the most. He killed his own father because he killed someone who was taking care of Yumiko. And Yumiko killed the other family member because he was going to kill the other villagers. And now he was being judged only because he was doing the right thing!
He punched with his left hand, not knowing he was close to the wall, breaking it, cracks can be seen in the immediate area of which he punched.
Once he ran out of kunai, he then began air boxing. Thinking of his father, who he also killed. Imagining if he could have done worse. He hated who he was. He felt like a burden to these people, to always be watchful of their own backs, just because they have heard that he killed two of his family members. And that's what really pissed him off the most. He killed his own father because he killed someone who was taking care of Yumiko. And Yumiko killed the other family member because he was going to kill the other villagers. And now he was being judged only because he was doing the right thing!
He punched with his left hand, not knowing he was close to the wall, breaking it, cracks can be seen in the immediate area of which he punched.