This episode provides some context and a couple of battles that help establish a few things. Thanks to Kotori's memories, we see what Kamui was like as a child and realize he was a shy, docile, and self-sacrificing boy. This helps us understand her and her brother's bewilderment at Kamui's current character, who, in the first battle of this episode, proves to be cruel and indifferent to the interests of others. We also learn a bit more about Hinoto, a seer who has prophesied the end of the world and Kamui's role through her dreams. Finally, we have a battle that helps explain certain things, such as what a Kekai is and why it needs to be used. Regarding the animation, I greatly admire how, at the time this anime was produced, they managed to create such fluid fight scenes and such detailed backgrounds.