The player who can't level up, 1

Eighteen years ago, a mysterious tower and portals teeming with hordes of creatures appeared on Earth. Now endowed with extraordinary powers, some humans seek to boost their strength and fame by battling these monsters—they are known as "Players." Gigyu is one of them, but his ambition is more modest: to amass enough wealth to lift his family out of poverty. However, when he discovers he is stuck at Level 1, his dream turns into a nightmare...