Invincible Summoner Who Crawled Up from Level 1: Volume 7

With the Ancient Flower raid event finished, Shinobu and his comrades leave the northern city. But just as they're about to regroup with Kaori, they're ambushed by rogue level 99 members of the Crimson Moon Brigade! Knowing he stands no chance against them, Shinobu opts to use his escape card: a Key to Agartha. If he can clear a boss rush of every demon lord in the game, he'll be able to power up...but how will he handle the unexpected guest who awaits him?