Maybe a Fake Gintama - Chapter 73: How Could There Be Such a Thing as a Love Guide!

Masterpieces such as 'The Divine Comedy', 'The Theory of Evolution', 'Encyclopaedia Britannica', 'The Theory of Relativity'...Born in the history of human civilization, possess mysterious and magical powers in another world!Original sin, biological evolution, mastery of all arts...By reading the secret tomes, one can gain a variety of powers!The only trouble for the people of the other world is that they find it difficult to understand the texts from Earth.At this time, there comes a librarian from Earth...

Cho Ryu Hyang was good at math from a young age. When he enrolled into the The Theoretical Maths and Martial Arts School, the teacher, Jo Gi Chun, recognized Cho Ryu Hyang’s talent immediately and took him in.

This novel is also known as From The Start, I Traded A Galactic Warship

After getting a trading platform three thousand years later, everything in the world has become an antique, worth a thousand gold.

But it was also learned that three years later, aliens invaded, human beings fell, and the dark starry era began.

In this era of unprecedented change in tens of thousands of years.

Shen Shi decided.

First trade a space battleship, and then talk about it.

then–

Battleships come to the world from outer space! Global shock! Starry Sky Era, open in advance!

- Description from novelbuddy

Shuu is a member of the literary club that can’t write. One day, he gets a mysterious message on his phone from a girl called Eina, and from that impulsive contact, they begin to exchange messages. They talk of things like their shared interest in novels and grow close. However, when they try and meet, they discover a shocking truth. Eina lives… not in the present, but five years in the past! How will their love develop, parted by five years of nights…!?