It’s a Japanese light novel series written by Seto Meguru-Sensei. It began serialization online on the user-generated novel publishing website “Shōsetsuka ni Narō.” (lit. “Let's Become a Novelist”)

The original novel began serialization online and five volumes have currently been released.

A manga adaptation has been serialized since 2018 and four volumes have currently released and vol. 5 is scheduled to release in the beginning of December 2020. The original novel has sold over 500,000 copied in total (as of May 2020), and an anime adaptation is scheduled to broadcast from January 2021 too! It’s a now-hot series, even becoming more famous and popular!

The story is set in the different world.

The main protagonist, Noir, gets a new job.

However, on the very first day when he goes to the company, he finds out that his new job as a librarian is taken by a son of the wealthy noble family……! Being shocked, it’s impossible to take it back because his family is the lowest level among the nobles.

Then his younger sister, alice, suggests to him that he should go to the “Hero School.”

The Hero School is very famous, offering various academic and hands-on training curriculum. Therefore, once they can graduate from the school, anybody can get a job.

However, even if he wants to go there, he needs money…… Actually, Noir chose to work because he didn’t have money to go on to the school, in the first place. Plus the admission exam is way too difficult that Noir is pretty sure that he cannot even pass it.

…… However, he does possess one rare “skill,” which is the magical ability called “great sage,” which only a couple people possess in the world. The skill is incredible, giving him various advice about the world (including unsolved cases).

However, he is not able to use the skill, because if he uses the skill, it gives him terrible headaches.

One day, Emma, who is his childhood friend, visits him.

Even though Emma is from the higher-level noble family than Noir is, she treats everybody equally no matter what level they are. Actually, Noir was supposed to work with Emma as a librarian but……

Let’s get back to where we were: Emma says to Noir from the knowledge about the old book which she has read before, “Great sage would demand that his wife kiss him, whenever he suffered from a bad headache.” Therefore, she thinks if they kiss while he’s using the skill of “great sage,” the headache might be gone or would never even happen.

A little nervous but not feeling bad…… Emma suggests to Noir that she should kiss him while he’s using the skill of “great sage,” to save Noir and get over this tough situation.

A liffle confused, Noir has also decided to use the skill of “great sage,” knowing that Emma will help him out by kissing him……!

Guuess what? While using the skill of “great sage,” he never gets headache……!

Unsure of what his future holds, he accesses the sage for advice on “how he can be strong enough to pass the admission exam of the Hero School in a short period of time”……!

The sage replises, “Try to find a secret dungeon.” (According to him,) there is a hidden “infinity dungeon” and Noir can make his wish ocme true by getting there.

Noir barely got to the designated dangeon, when the voice screaming is being echoed from the road, leading to the “hidden dungeon,” which the sage mentioned…… Repressing his emotion, wanting to go back home, Noir finally gets to the hidden dungeon……

Then he sees a super beautiful woman, standing, tied by the chains.

As he is ordered by the woman, Noir touches her head, when he starts to look back on something.

The woman’s name is Olivia. According to her, she is a suuuuuuuper duuuuuuuuper great adventurer and has happened to find that hidden dungeon. Then he killed all the monsters, which were in that room, instantly. However, the trap was activated because she beat the monsters. Since then, she’s been locked in that room for 200 years.

Clumsy? Unlucky……? Noir, who just hears her past, which he cannot give any comment on, is now trying to save her. However, the trap seems quite a high level one that he cannot take that off easily……

The reason why Olivia called Noir…… That’s because……?