Naruto System in One Piece - Chapter 126

Having a rough life growing up, Wang Tong had numerous dreams of living a better life. However, his alcoholic foster father sells him off as a space settler of the distant planet Norton for some pocket change. Soon after his arrival, the Zergs overran the planet and obliterated its defenses in a matter of minutes. What awaited Tong on Norton was more than just an unbearable environment – its gravity alone was five-times stronger than earth – there were also swarms of bugs, constant hunger, thirst, and desolation.

While he lives a year of total carnage and survival, humanity’s Confederation eventually overcomes the Zergs on Norton and the powerful survivor Wang Tong is given a recommendation to a once famous, but now dying military academy where he begins his life anew.

- Description from Novelupdates

In a world where dungeons were an essential part of it, Rein was trying to conquer as many as possible. They were the key to gain powers in the fastest possible way. So, to reach his full potential and to become the strongest, he became a great dungeon conqueror.With his trusty friends and lovers, he was definitely going to reach the peak alongside everyone. Join Rein and see how he went from strong to stronger and then the strongest.__________________1. The harem would not be too large(I'm not sure how many but probably just 4-5 main and few other here and there). All the girls would be getting their time and story.2. The story is starting when the MC is in the middle of his growth stage and not at the very beginning. But his beginning will be mentioned in the story in some form.3. I don't think I need to mention this, but obviously it will not have any NTR, rape or that kind of stuff. It is actually quite a wholesome story focusing mainly on adventure, action and bit of romance and slice of life.

“Primum non nocere.”

For three years Calix suffered from the Backlash of his undecipher Term Attribute. As he couldn't use his unique power, he went through series of misfortunes which caused him to lose his self-esteem. However, one day, he was caught in an incident that led him to awaken his hidden power(luck).“The fuel of my Term Attribute is sexual practices with the opposite gender?”