It's the golden age for treasure hunters—adventurers hungry for wealth, fame, power, and glory, who risk their lives in treasure vaults throughout the world.
 
“Let's become treasure hunters.”
 
Krai and his childhood friends swore to become the greatest of them all, but that dream should have died the day Krai realized he wasn't cut out for the job! Yet expectations continue to mount, right along with Krai's fear for his life. While his childhood friends climb closer toward their dream, this grieving soul has one simple wish: to pack it all in and retire!
 
(Source: J-Novel Club)

Let This Grieving Soul Retire