AntiMagic Academy “The 35th Test Platoon” - Volume 10, Chapter 3 - Red Glare

... els under the border were dug in a rush during the war and turned into a wide labyrinth, not even Inquisition had grasped it fully.

It was a perfect escape route and a hiding place for criminals.

Hayato has memorized its map. The location he was in was used for transportation of goods using trolleys during the war. The closed space and moisture felt in the air would normally wear away anyone. It was unthinkable anyone would set a foot here.

Not bothered, Hayato proceeded ...