|I've read both, I can't see much similarities. Mostly just discrimination. Probably because I read the novel, so there's more plot development there. As the chapter progress, you'll see the difference.
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Tatsuya's one badass motherfukker and he's not one to let himself get bullied. He's not helping them per se. He's just a student doing his job, and that's only because of his sister. Truth be told, I can't find any similarities between the two MC.
If you mention characters and their characteristics, it's not a very strong point for similarities between the two manga. It's pretty much stereotype characters with different blends, no one (not very much) wants to read bland characters with no characteristics.
Not that I don't like Iris Zero, I think it's cute.