[Machine Translation] The long-awaited visit to the Land of Dwarves! But the road is not a simple one...? Yoon had a tough time with the boss MOB Doppelganger in the Sense Expansion Quest ( A challenge letter from inside the mirror ). He was at his wit's end, thinking that it was because he was not good enough, but it seems that this is not the cause of the problem...? With his one-of-a-kind strategy, he is ready to take revenge! Then, a large-scale expedition by Yaoyorozu (Yaoyorozu) took them to an underground canyon in the land of the Dwarves. The tough athletic challenges are confusing, but with the help of Claude, you will be able to push forward...! The fun of OSO is not just about clearing the path! Volume 23 is full of challenges and exploration!