I am that male friend in the harem story - Chapter 341: Haruno Yukinoshita: "My little sister isn’t cute!"

Marked by the cursed Darksign, Naruto Uzumaki finds himself tethered to two worlds: the unforgiving lands of Dark Souls and the shinobi realm of ninja. How will a world of Dark souls face a Chosen Undead with chakra? And how will the shinobi world confront a warrior reborn in the Lands of Lordran?

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.

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

Shenwu mainland, Yangwu worships God. A generation of Tianjiao, Wu Sheng was born again. Too really water, refining the body. Boxing the world, feet and arrogance. The celestial emperor, the law is empty. “Dare to despise the brothers, all killed!” “The woman who dares to move the brother, has been sleeping!” “Brother is just a myth, no one!” – from the quotations of the Emperor Lingfeng. The Supreme Demon is a very popular fantasy fantasy type written by the author, and tells the vivid story of the Supreme Devil.

- Description from zhuishubox (translated)