Isekai / Reincarnated TRASH [DO NOT READ!!]

Ecchi, Harem
adapted to anime
https://www.novelupdates.com/series/arifureta-shokugyou-de-sekai-saikyou-ln/

https://www.mangaupdates.com/series/ld01a4t/arifureta-shokugyou-de-sekai-saikyou-zero

Harem, Polygamy
https://www.novelupdates.com/series/cheat-magician-life-that-started-from-being-judged-useless/

https://www.mangaupdates.com/series/he3wjyx/hazure-hantei-kara-hajimatta-cheat-majutsushi-seikatsu

Reverse Isekai. Harem
https://www.novelupdates.com/series/the-world-is-overflowing-with-monster-im-taking-a-liking-to-this-life/

https://www.mangaupdates.com/series/czu8wzw/monster-ga-afureru-sekai-ni-natta-node-suki-ni-ikitai-to-omoimasu

Harem? web novel only have 66 chapters
reincarnated to game
https://www.novelupdates.com/series/last-boss-wants-to-try-retiring-ill-pretend-to-be-defeated-by-the-heroine-and-try-to-live-freely

https://www.mangaupdates.com/series/klm3m9g/last-boss-yamete-mita-shujinkou-ni-taosareta-furi-shite-jiyuu-ni-ikite-mita

Harem
https://www.novelupdates.com/series/the-adventure-of-the-boy-with-a-mind-of-a-middle-aged-man/

https://www.mangaupdates.com/series/lfg2pzt/karada-wa-jidou-nakami-wa-ossan-no-nariagari-boukenki

Reverse Isekai + Tensei, Harem
Axed/Cancelled/Discontinued
https://www.mangaupdates.com/series/o58w2ro/goodbye-isekai-tensei

Harem, Polygamy
https://www.novelupdates.com/series/black-summoner/

adapted to anime
https://www.mangaupdates.com/series/ii7msyi/kuro-no-shoukanshi

Harem
https://www.novelupdates.com/series/the-genius-but-weakest-demon-tamer-wants-to-return-home-separated-from-his-strongest-servant-he-was-sent-to-an-unfamiliar-land/

https://www.mangaupdates.com/series/z8yfom8/tensai-saijaku-mamonotsukai-wa-kikan-shitai-saikyou-no-juusha-to-hikihanasarete-mishiranu-chi-ni-tobasaremashita

https://ncode.syosetu.com/n4224gn/

Harem destroyed the isekai world building setting
https://www.novelupdates.com/series/banished-reincarnated-duke-wanted-to-cultivate-fields-leisurely-in-the-frontier-forced-to-excel-in-domestic-affairs-as-more-people-flock-to-his-territory-despite-his-warnings/

https://www.mangaupdates.com/series/23ghm8w/tsuihou-sareta-tensei-koushaku-wa-henkyou-de-nonbiri-to-hatake-o-tagayashitakatta

https://comic-walker.com/contents/detail/KDCW_KS13202077010000_68/

Harem
https://www.novelupdates.com/series/will-i-end-up-as-a-hero-or-a-demon-king/

https://www.mangaupdates.com/series/ruprr5z/ikitsuku-saki-wa-yuusha-ka-maou-ka

https://www.mangaupdates.com/series/ruprr5z/ikitsuku-saki-wa-yuusha-ka-maou-ka