MTL - After Binding the Barrage, My Friend and I Wore Red and Black - Chapter 26

He lived like a king, died like a grandpa... and woke up as a bratty villain inside a fantasy novel.Nice.Born into the mighty Arkanveil family, he’s expected to grow up spoiled, arrogant, and doomed. But sorry, fate — he’s got better plans.Armed with a broken Proficiency Panel, two god-tier Traits, and the mind of a seasoned conqueror, he’s here to rewrite the script.Demigods plotting. Councils scheming. Demon Emperors laughing.They’re all just EXP waiting to happen.Pretending to be a clueless baby genius, he secretly trains, conquers, and stacks power like a final boss.Because this time, the EX-Rank Villain isn’t playing to survive.He’s playing to win.The world’s greatest families have no idea what’s coming. But hey... they’ll find out soon enough.“EX-Rank problems require EX-Rank solutions.”

Sure, the world is ruined, but I’ll live my own way. Of course, luxuriously and gorgeously.

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.

This is the story of a modern sailor who was accidentally reborn as a soldier of the Brazilian Expeditionary Force, and finally became the largest plutocratic family in Brazil by virtue of his foresight.

- Description from novelbuddy