Emperor's Domination (Web Novel) - Chapter 6598: Who Are You?

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.

Awakening to a post-apocalyptic world infested with zombies and mutated monsters, Alex makes a startling discovery: he possesses a system that grants him access to unlimited resources every day.【Congratulations, you've received unlimited bottled water.】【Congratulations, you've received unlimited 9mm bullets.】【Congratulations, you've received unlimited cold medicine.】...With each system notification, Alex's chances of survival soar while others struggle to stay alive.As everyone else fights for their lives, Alex finds himself living in luxury, residing in a lavish mansion where he leisurely sips red wine and savors grilled delicacies amidst the chaos of the end times...

Yo, Hi! I’m Frank, I made a deal with a demon to pay me some money for receiving a guest for a few days every week.
I had no idea about what I have done.
On May 1st, Conan ‘the God of Death’ came to my house. I was forced to let him in and we get involved in a criminal case.
On May 8th, Bruce Wayne ‘Batman’ came to me. I was forced to follow him to fight crime.
On May 16th, Hannibal Lecter, The Silence of the Lambs, came to my home. I can only say that I really can’t stand my guests.

- Description from Novelupdates