Kujibiki Tokushou: Musou Hāremu ken - Chapter 286

Monsters, both human and beast, surrounded him. He needed power to survive this new world... but he arrived as a mortal.One moment William was at work. The next, he was captured by lunatics.He had never believed in the fantastical, but he had no choice after finding himself in another world surrounded by demonic cultivators trying to extract his soul. If he couldn't find an escape, his journey would end just as abruptly as it started.William was inches from death when a benevolent cultivator saved him from that fate. Seeing his pitiful state, the cultivator decided to give him an opportunity in the form of a tool: A system to guide him on the path of cultivation.William would use it to claw his way to the peak of the cultivation world.

It’s not always the Asians who get isekaied. Very rarely does an American get chosen, though the lords of isekai have reasons for that. It’s time for John to remind them of those reasons.This story started as a gag. It is no longer a gag.

Crossing into the world of Naruto, and acquiring the One Piece system, with all the powers of the world of One Piece, swordsmanship, devil fruit, domineering.

-Do you think that your fire is very powerful? I have the burning fruit.

-Do you think that your thunder is very powerful? I have a thundering fruit.

-Do you think that your otter is very powerful? I have the frozen fruit.

-Did you said you want to die? Don’t worry, I also have a nickname: Death Doctor.

- Description from Novelupdates

In this period where countless supporting lead actors always attempt to counterattack, turn over a new leaf or simply refuse to take up the role, his purpose of existing is to fill the role of a good supporting male lead and uphold his duty to the best of his ability. To add the needed lustre to storylines and this world. Only, it’s a pity that someone who is not afraid of god-like enemies will be afraid of pig-like teammates.

Bitterly, he realises that for some unfathomable reason, he is being bothered time and again by a bastard who refuses to follow the script… In order to walk the path of a good supporting male lead, he engages in a battle of wits and courage with that person. Loving each other and killing each other, one ultimately cannot escape fate’s teasing– why is it so difficult wanting to be a responsible and diligent supporting male lead?! QAQ

- Description from novelupdates