The First Large-Scale Invasion was an attack by Trion Soldiers in Mikado City four and a half years before the start of the series. It killed over 1200 people, and over 400 people are still missing.
The attack was carried out by an unknown Neighbor nation on Mikado City. Conventional weapons proved ineffective against the alien invaders. In just two days over 1200 people died, and over 400 were missing, some of whom were presumably abducted. The eastern portion of the city was destroyed, causing many to lose their homes. The attack was ended by Border, which went public after the incident.
- The large-scale invasion started on a Sunday.
- World Trigger Anime — Episode 22
- World Trigger Manga and Anime — Vol. 1 Chapter 3 (p. 13) and Episode 2.
- World Trigger Manga — Chapter 84 (p. 7)
- World Trigger Manga and Anime — Vol. 1 Chapter 1 (p. 5) and Episode 1.
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- World Trigger Manga and Anime — Vol. 17 Chapter 144 (p. 11) and Episode 80.