Chainsaw Man: Starting with the Dark-dark Fruit

[Multiple female leads (Four Horsemen of the Apocalypse, Little Red, Reese)] + [System] + [No angst or torture (just for fun)] + [Not a crossover (only the Chainsaw Man world)] + [Gender-swapped Hayakawa Aki]

Undertaker Su Ze is transported to the world of 'Chainsaw Man' and starts off with the Dark-Dark Fruit ability from One Piece!

(Necessary settings will be explained; this will not affect your reading experience if you are not a fan of the original work.)

(Warning: To achieve the multiple female lead ending, the timeline and some character settings have been altered. Original fans, please forgive me. Author Feiwu is here to support you.orz_)