Technically a sequel, but happens simultaneously with the previous story and does not require reading it or any other entries in the series.

Returning home for a summer break, Yona finds Yakyakistan on the brink of a civil war. While Prince Rutherford wants to open his country to the world and ally with ponies, a group of traditionalist Yaks under Prince Bradford want to return to the traditional isolationism.

As the threat of War of Two Brothers looms over Yakyakistan, Yona finds herself surprised by the stubborn stupidity of some of the yaks she used to look up to. The Student of Friendship faces her greatest challenge at the doorstep of her home, but she has no doubts – she is Yona, and Yona is the best! She will stop this stupid war before it starts!

Prince Rutherford could already feel the incoming headache.

As usual, minor Equestria at War references in names and locations. Knowledge of EaW not required at all to enjoy the story.