Kansutoppu!

This story follows Ryua, a girl whose village was razed and villagers slaughtered by demons. After escaping the village, Ryua wandered in the mountains until she stumbled upon a dungeon. A 100 floor dungeon, unknown to others. The 100th floor, deep underground, was occupied by the in the guise of a senile old man . After a difficult battle, she found herself boosted to an incredible strength and escaped the dungeon. This follows her adventures afterwards.

Note: Kansutoppu is an abbreviation of in Japanese. It’s not “can’t stop”. is when a stat reaches the maximum, and the counter for it stops increasing.