Cringeworthy, brought to you by Natsuki Subaru.

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"I'll shut your mouth~~~~~ with mine~~~"

二息歩行

This is an interesting poll. I agree with meredithbecca.

For example, "Hopeless/Gloomy" characters are unappealing to me, unless it's Itoshiki-sensei of Sayonara Zetsubou-Sensei. I answered "Unrealistic", because I can't stand characters that act like no person ever, but too late realized that it meant that the character has an unrealistic outlook. So I should have answered either "Emotionless" or "Cringeworthy".

I've stopped reading stories because the main character behaved unrealistically. Usually it's a shoujo where the main character is unrealistically stupid/naive. I've read a few stories where I'm just thinking "there is no way someone can be that stupid. why does she never learn from her mistakes?" Or I'm reading a story, and I'm thinking "there's no way someone would choose to do that". Stories don't have to be realistic, but I can't read a story where I doubt the way the characters act/react.

I never remember to stop reading a manga because of a particular main character's character, but if anything maybe Cringeworthy seems to be my answer since it's kinda vague and subjective mmm...

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Dense and Naive ones are the most annoying... It is hard to make me cringe... in fact I like to discover new perverted fetishes... When guy is Stupidly Dense it is a show stopper for me... Stupid is ok, but not always...

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It is kind of a weird question; I've never dropped anything because of the main character specifically, more just how they/their behavior is framed in the context of the story. Like, there are archetypes I definitely hate, or characters I think are total tools, but unless they (drastically) interfere with the quality of the story, I'm not necessarily going to drop it. It might be the tipping point, sure, but not the primary deciding factor. There are lots of characters I love who happen to have traits I'm not a huge fan of, and there are characters I should by all means love but don't because they just aren't that interesting. It all comes down to the competence of the writer and the story quality.

For the record, I went with "cringeworthy", since the second-hand embarrassment is just too real.

I think everyone would pick cringeworthy as the blanket reason. For myself, the MC would have to have multiple obnoxious traits like being a dumb cowardly crybaby to qualify.

Generally, one or two flaws can be redeemed by good traits or good side characters but more than that is a stretch.

I do drop series, especially if I haven't followed it for a long time. What gets me started would be the basics like intro, art, plot, etc. But the MC could make me drop series. As for which of the choices to vote for, I can't choose one. I guess around a third of them apply? I don't like male MCs who don't act like men. That is, crybaby, unreliable, extreme cowardice (a bit of cowardice is good for health and increases longevity). Then there are the stupid, naive, dense, goofy MCs. I can't stand them for long. I have my own mental health to consider. The above two groups are just cringe-worthy as a whole.

Finally, there are the unrealistic and inconsistent MCs. They don't walk the talk. They have much to say before ever being able to accomplish anything in the story. Speaking of grand ambitions while taking two steps back for every step forward. Somehow challenging superpowers without any reasonable level of firepower to rely on. It's this last category that makes a story hopeless. A cringe-worthy MC could grow up and man up at some point, even if I'm not willing to stick around till then. But an MC who is fundamentally flawed in his beliefs, character and personality, has no way of redeeming himself. Such an MC will need the author to prop him up the whole way. In other words, an inadequate character to take the main lead. I would say Naruto and many other MCs of the most popular action manga fit into this category.

I assume flawless/perfect equal to being a sue.

I chose Dense/Naive. There are just some mangaka's that make the main character so incredibly dense, that even if someone spells it out to them, they won't come to the obvious conclusion. I just feel like.. how are they that dense and how did they live X amount of years on Earth? I read (some) shoujo mangas now and then when I'm feeling a bit masochistic.

This.
I'd hate some of these traits in real people, but it really all hinges on how it was handled in the story. There should've been an option for none and all, depending on the character, plot and writing.