I'm looking for a manga where a character (preferably a main character) is obsessed with delivering his "justice" to the point where he blinds himself to anything else. Bonus points if the character is betrayed by his "justice" in the story as well.

An example would be Emiya Kiritsugu from Fate/Zero, who became a cold blooded champion of justice that would kill 100 to save 200 people

Another example is Takasu from fukashigi philia, who goes almost ballistic when he sees someone who stands in the way of his ideal justice of "cleaning up" of the city.

Edit: I prefer for it to be shounen/seinen.

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Being alone is only lonely if you want it to be.
Staying in lucid delusion for an eternity.

Yokokuhan- has the mc delivering personal justice to people that wrong others but the crimes aren't enough to be deemed criminal...He then posts videos of him delivering this justice online and often he makes the punishment fit the crime but also oversteps the boundaries of right and wrong whilst doing it.

Liar game- I think the mc might fit

Samurai drive-secondary mc becomes obsessed with the death of his idol and begins delivering justice on the streets at night to those he sees as enemies. (or something)

Adamas-maybe...she'll do anything for the sake of diamonds.

zetman the two main characters have their own sense of justice. One of them fits your description perfectly.