Zach Loud, his brother Lincoln, their sisters Lori, Leni, Luna, Luan, Lynn, Lucy, Lola, Lana, Lisa, and Lily, and their parents Lynn Sr. and Rita are in Japan to hang out with Touko Mishima, Rinko Mishima, Hajime Tachibana, Satoka Sagawa, Misako Mishima, and Misako’s 5-year-old son Zach Mishima for the summer. While they’re getting stuff ready, Zach is on a walk till two gentlemen take him to the warehouse to see the nightmare giantess Pai Pai who is Zach’s twin sister.