Books in the Mushoku Tensei: Jobless Reincarnation (Light Novel) series

FATHER AND SON BRAVE THE LABYRINTH!Rudeus and Paul must descend into the deadly depths of a Teleportation Labyrinth to rescue Zenith. The father-son duo makes short work of deadly beasts and ancient magical traps, but it's the terrible truth at the Labyrinth's heart that proves the greatest threat of all. What happens when all hope is shattered beyond recall?