Tempting Fate - Chapter 126

Lambert, one of the great generals from Regios kingdom was suspected for planning a rebellion against his lord at the end of unification war, he died an unnatural death. Two hundreds years later, when the era has changed and Regios kingdom entered it’s peaceful era, he accidentally revived as a demon called Undead Knight.. Lambert whose entire body was wrapped in a flashy Demon Metal[Organ] set out on a journey to punish the wrongdoers while enjoying the peaceful sight of Regios kingdom. But…….. This peaceful era was basically an easy mode for Lambert, the greatest general of the chaotic era.

With the revival of spiritual energy and the breakdown of the order of species, it is a difficult test whether human beings can still stand at the top of the biological chain.

(There is already an old book, The Strongest Descends in the City, you can read it.)

- Description from novelbuddy

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.