The supporting character's harem is very normal - Chapter 36 Sorry, Lathel...

Tang was cheated by her husband who got another woman pregnant. Tricked by the mistress and mother-in-law, she had been criticized by the public and kicked out of her husband’s family. Then, there comes Su, who showed up like a saviour for her, prevented her from all the difficulties that her ex’s family made to her. He held her in his arms, haughtily said to them, ‘It will only be me that can bully my girl! Anyone who dares to bully her is opposing me!’ She was shocked. And her mother-in-law said she was a wanton woman. After that, he was always protecting her, treated her preciously. He made her realized that even the second marriage could also make her so happy!

- Description from Novelupdates

“A modern online novel writer who had been struggling finds themselves transported into the world of One Piece, becoming a 10-year-old child.After a series of events, Ryuen arrives at Cocoyasi Village. The protagonist possesses the Tori Tori no Mi (Bird-Bird Fruit), Mythical Zoan type, Phoenix form.After undergoing a rebirth (Nirvana), the protagonist's transformation no longer involves turning their hands into wings, and the fruit's power becomes even stronger!From the moment they reach Cocoyasi Village, the protagonist and Nami embark on an adventure, traveling from island to island, indulging in food, drink, and fun. Along the way, they also help the poor by taking from the rich, because, after all, Bellmere’s family is still...”

mc gets transmigrated to Fallout New Vegas with the merchant system. let the questionable adventure begin.

A man reincarnates in the body of a boy who suffered a tragedy, only to realize that he is in the world of My Hero Academia. What's even stranger is that his quirk seems to have the abilities of Nen and Haki.