Dungeon Crawlers Academy. 1, Into the portal

"When four kids went through a mysterious portal, they discovered an endless dungeon full of treasure, monsters, and magic! They returned home as heroes. But when adults tried to enter the portal, they couldn't. Only kids were granted access. And so the Dungeon Crawlers Academy was born: a school devoted to training young adventurers to explore the dungeon and bring back its fabulous treasures. Nathan always dreamed of being a hero. A dangerous e...