Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka English Volume 1-4 (PDFs and epubs)

Light novel is currently license by Yen Press.
http://www.yenpress.com/is-it-wrong-dungeon/

http://www.jcafe24.net/index.php?topic=37891

PDFs and epub versions are both included.
Nickname: Danmachi
Credits: Solitary Translations

==== Plot ====
The huge labyrinth city, Orario, is the gateway to the huge underground maze commonly known as the “Dungeon”. Its strange name causes excitement, a place to gain honour, and maybe even a romance with a pretty girl. A place where people hold their breath, hoping to gain all they wish for, a place where a solitary young man meets a little “god”.

“Alright, Bell-kun, follow me! It’s time for the “Familiar” initiation rite to happen!”
“Yes! I’m going to get stronger!”

The fated meeting of a boy who wants to become an adventurer, and the failed god who doesn’t even have a single follower.

This boy’s journey as written by the goddess, “Family’s Legend” (Familiar’s Myth)

Source: Baka-Tsuki