Shigemori Sumimura takes Yoshimori to the family vault. He gives Yoshimori a small, wooden box, and tells him to try to break it with a Kekkai. Yoshimori tries immediately, but the box is totally undamaged. Shigemori explains it is a "no thought" box, a training tool created by Tokimori Hazama, and that breaking the box will be the first step of Yoshimori's training. Yoshimori finds that multiple Kekkai at once have no impact on the box. Dropping the iron training boulder on it has the same result.