Since watching Mahouka, I can't help thinking of Our Lord And Savior, Shiba Tatsuya every time I hear Mary Sues come up in anime.
It's almost like the writer went through a Mary-Sue checklist and made sure his hero ticked all the boxes. I would not be surprised in the least if this guy got his start by writing fanfics for other light novels or mangas.
First up, the name. It's basically a slight distortion of the author's name, Satou Tsutomu. Dodgy name : Check. Blatant author self-insertion: check. And the whole plot basically reads like the disenfranchised misunderstood highschool boy gets one over on the popular boys, and gets all the girls fawning over him. And even that comes across a bit lame: "Haha all the girls want me, but I'm too cool to even react: how's that feel now, highschool girls who ignored me?" While simultaneously showing up all the adults in the world, and being an unsung genius at everything.
Just to make it extra-clear that he's above everyone, the author decided not to have him challeged by any villains stronger than a wet paper bag. But he has basically God-like powers to nuke entire cities just by looking at them and literally raise the dead without limit. (The author explains why he doesn't use the raise-dead ability all the time to save people with the most infantile reasoning ever: each time he raises the dead he feels 150 times the pain of that person. But he's not even shown blinking any time he uses it, so this excuse is just plot convenience as to why Tatsuya only uses it to help his friends, and not humanity as a whole. Basically he doesn't like pain, so refuses to use his Jesus-power on anyone except his pals. it's pretty much logic a 12 year old would come up with as to why the hero isn't sharing his power in a logical fashion)
Hell, he has the ability to automatically heal ANY wound he suffers instantly. So he's basically immortal, and in a world full of powerful magic. For any remotely competent writer, this sort of power would be invoked all the time, so that the hero could take on supernatural enemies, take massive damage but keep fighting. But not in Mahouka. No, this writer can't even tolerate his IMMORTAL hero taking any damage in a fight. He needs to use this ability exactly one time, and it's to avoid him losing a friendly sporting match so his school can get a trophy.
You'd be hard pressed to write a more blatant Sue story deliberately.