Dragonborn Saga - Chapter 723: 21 Years of Planning

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.

Let’s fight! Go! Who am I afraid of with a chip that turns into a brain cell? ! Get promoted and get rich! The nest treasures are all mine!

- Description from novelbuddy

Meet Sora and Shiro, a brother and sister who are loser shut-ins by normal standards. But these siblings don’t play by the rules of the “crappy game” that is average society. In the world of gaming, this genius pair reigns supreme, their invincible avatar so famous that it’s the stuff of urban legend. So when a young boy calling himself God summons the siblings to a fantastic alternate world where war is forbidden and all conflicts–even those involving national borders–are decided by the outcome of games, Sora and Shiro have pretty much hit the jackpot. But they soon learn that in this world, humanity, cornered and outnumbered by other species, survives within the confines of one city. Will Sora and Shiro, two failures at life, turn out to be the saviors of mankind? Let the games begin…