I only read the story up to the warship island arc with the Dragon and Apis.
The story feels forced. The MC power fluctuates. One chapter he achieves the level of cutting steel or "exchanging blows" with Hawkeye then next he can't cut through Arlong. One chapter he can cut through the sea then next he gets bugged down by a fleet of marine.(Nelsons Fleet).
The author probably want to make the story more dramatic but at the expense of the MC becoming weak.