Border Saga

Border Saga is the first Saga in the World Trigger series. The Saga is mainly about the dealings of Osamu and Yūma takes to keep Yūma from being captured by Border. The saga introduces Main Characters. It shows Osamu beginning to start a bond with Yūma. Yūma and Chika join Tamakoma Branch and Mikumo Unit Is formed in order to venture out to the neighbor side and rescue Chika's friend and Brother.

Arcs
The Saga currently contains four arcs:
 * Introduction Arc
 * Black Trigger Retrieval Arc
 * Rank Wars Arc
 * Third Trion Soldier Invasion Arc