The Benefit of the Level Up (レベルアップの恩恵) is the fifty first chapter of the DanMachi manga.
The day after Welf joined, the party headed to the 11th floor of the dungeon for the first time. Welf's motive for joining was to obtain the Blacksmith Development Ability that would also be useful to Bell as he was his customer. Normally he would've gone with his other Hephaestus Familia members to explore the dungeon, but for some reason they refused to go with him, forcing him to gain help from a different Familia. Lili wasn't happy about Welf joining their party, claiming that Bell was bribed, yet became interested when she found out that Welf's surname was Crozzo. She began explaining what the Crozzo were, but he changed the topic while he readied his weapon to fight. The party fought against a group of Imps, Orcs, and a Hard Armored, with Bell confident that he was catching up to Ais.