I knew of 5 manga that had multiple endings, 4 of them are harem, so I googled and found one more with We Never Learn. The most involved of the bunch. That is more than enough for a category so I created Multiple Endings. Seemed the cleanest option to me but I am open to feedback on the name.

This isn´t just a video game and VN anime adaptation quirk (though OVAs) but Btooom! is game-y and the others are all harem so the theme remains. Do YOU know of any other example? Assign the tag or simply name them here so that an updater can do it for you. I am curious about what else is out there! This is quite the phenomenon and a recurring question on anime/manga sites. My tag with our large library would lead to a one-stop solution link.

What we have so far: https://www.mangaupdates.com/series.html?category=Multiple%20Endings
Bokutachi wa Benkyou ga Dekinai - Harem ending routs begin with Vol 16?
Btooom! - Light and Dark Vol 26
Fuuka - Special Edition Volume for harem endings
Kimi no Iru Machi - Special Edition Volume for alternate chapter 200 harem endings
Koi to Uso - 2 versions of Vol 12
Sundome!! Milky Way - Vol 10 has a separate entry with harem endings

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I also read EU/US comics and am a librarian.
Manga-Masters, My ANN-Lists + Imdb

Honeymoon Salad - Vol. 5 has short extras / omake at the end for different endings.

S - Kimi to, Kanojo to, Unmei to - Separate ending routes for three of the heroines.

Sadly, S - Kimi to, Kanojo to, Unmei to, is not translated fully in English. Not sure if there's another route for a harem ending.

I've added the categories to the listed manga myself, but I'm not quite sure Honeymoon Salad qualifies. As stated, they're more like bonuses the author threw in.

Last edited by featherfang at 9:22 am, Apr 12 2023

Omake are jokes by design. Tetsuwan Birdy (II) has an omake in every volume that runs through its sequel where the whole manga is a Tokusatsu production but no one would call that an alternate continuity. Parody chapters as in Sayonara Zetsubō Sensei where the protagonist dies can´t count either.

That said. I have no idea if Honeymoon Salad count or not after checking back with Chapter 40. Maybe? The epilogues cancel each other out after all. If in doubt apply as they exist (I remembered No 3 being the manga´s ending, lol). They are in the final bound volume instead of being hidden away on Pixiv or whatever. The voting system is there for a reason.

Dear lurkers, pls upvote all mentioned entries so far (Honeymoon Salad could be an edge case) to make the tags stand out. These are VERY noticeable distinctions and there is no way that no webtoons with alternate endings exist.

________________
I also read EU/US comics and am a librarian.
Manga-Masters, My ANN-Lists + Imdb

I know some of the suggestions, mangas like this, author would make a chapter or a volume for fans' satisfaction, like aot or quintessential quintuplets which has different endings in anime and there's mangas with added name, if remember one was who time travel to elementary school.
And there are ones who shows the ending on every choice they make, mostly romcom.

It wouldn't apply if the anime has a different ending, it has to be a manga with alternate chapters, essentially.