Gunshi wa Nandemo Shitteiru  

The strategist knows everything, 軍師は何でも知っている

Kurei Yukito made a wish before passing away that he wanted to be able to understand others better in his next life. However, when he woke up, he found himself in a different world at the start of a war and was given a cheat skill due to a misunderstanding of his previous wish. Despite having poor social skills, Yukito worked as a messenger between countries for the rebel prince. He desperately tried to fulfill his dying wish by living in this new world. Nevertheless, despite being surrounded by war, hints of it gradually began to creep up on him.