Adding Friends Can Make Me Stronger - Chapter 204

When The Cute Kunoichis Spied on Their Teacher's Secret is a light novel written by Kazuma Kamachi and illustrated by Ryuushi Tajima.

The story takes place in a world where Japan never ended their isolationist phase, and agents from foreign powers are always threatening to steal the country's advanced technology. In order to combat this threat there has been a resurgence of ninjas that use Strategic Martial Arts, techniques that combine cutting-edge modern technology with a traditional foundation of martial arts and ninjutsu. The story follows Souha Sugiyado, a 17-year old ninja instructor and former ninja prodigy who was forced to retire from active duty by the wounds he suffered in his last mission. Souha's four students are all kunoichi who have all gained the rank of Elite Ninja, the highest official rank available to ninja. However, one day two Shogunate ninja approach him with the news that his four students have gone rogue and have stolen a portable modular nuclear reactor, and thus they ask for his help in bringing his students to justice.

“Look at him,” someone snickered from a few rows over. “Smells like he sleeps in a dumpster.”“Probably does,” another voice added, louder this time. Nox just stared at his textbook, the words blurring. He had heard it all before.Then, Mark, one of the main reasons his life was a living hell, swaggered past his desk. Mark always had a smirk on his face. “Oops,” he said, not even trying to sound accidental, as a full cup of bright orange juice tipped over, splashing all down the front of Nox's already ruined shirt. The cold liquid soaked through instantly. Laughter erupted around the room. It was loud, clear, and mocking. Nox slowly looked up. His eyes landed on Ms. Joy, who was watching the whole thing. She had seen Mark deliberately pour the juice on him. He raised his hand, a small, tired gesture. “Ms. Joy,” he said, his voice flat. “He just poured juice on me. Are you just going to ignore it? Again?.” Ms. Joy looked at him, then at Mark, who was now theatrically wiping his hands. A small smile played on her lips. Then she chuckled. Just a little airy laugh.“Oh, Nox, don't be so dramatic. Boys will be boys, right Mark?” Mark puffed out his chest. “Yeah, Ms. Joy. He's just sensitive.” The class laughed even harder at that. Ms. Joy joined in, her laughter ringing out with theirs. Hearing them all, hearing her laugh, something in him finally snapped. It wasn't a loud break, more like a quiet, final click. He realized it then, with a cold, hard clarity. No one was coming to save him. No teachers, no police, no parents he never had. No one cared. If he wanted this to stop, he would have to be the one to stop it. He was the only one who could.His face remained blank, but his mind was suddenly very clear. He reached down slowly, his hand going into his worn-out school bag. The laughter died down a little as a few students noticed his deliberate movement, a strange stillness about him. He pulled out a gun.The classroom went silent. Utterly, completely silent. Mark's smirk vanished, replaced by wide, terrified eyes. Even Ms. Joy stopped laughing, her face paling. “What… Nox, what are you doing?” she stammered, her voice suddenly shaky. He didn't answer. He looked around at their faces, one by one. Fear. He saw fear now. Good. He was ready. He was going to make them all pay. He was going to end it, all of it.Just as he was about to raise the gun properly, a bright blue screen appeared right in front of his face. It was translucent, and only he seemed to see it. [Congratulations! You have met the requirements!] [1st Player Chosen!] [You have won the System!]

The Immortal Path led to Longevity and Sovereign was heading in ease. When the Longevity was no longer in ease, all living beings were just prisoners. Conspiracy, internal strife, and the invasion of the others, all of it emerged together. 

In such a world, there was such a young man. He made his way upstream, stepping on blood, defying the emperor, destroying the various kings, and slaughtering his way through the hundred clans to form an Immortal Path towards the throne of Sovereign! The Immortal Path was endless, while the Sovereign was limited. He used his blood to forge his immortal legend.

- Description from Novelupdates

There are always four kinds of people in the traditional Mary Sue world. The Male Lead, the Mary Sue female lead, the woman who never wanted to see the female protagonist live a good life, and the infatuated man willing to destroy heaven and earth to get the female lead.