MTL - Humans Are Falling Apart, Just In the Moon, Science God - Chapter 36

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

“You call yourself a hero? After your greed killed my sister?”What would you do if all of your friends, everyone you ever loved besides your sister, died in front of you?What would you do if, because you were weak, everyone hated you and considered you a Wasted, someone who hurt humanity's chance to survive extinction?Adam continued fighting despite this abuse, because he still had 1 simple goal: even if he was nothing more than cannon fodder or wasted potential, he would keep his sister safe.But then, it wasn't the Kaiju or apocalypse that killed her. It was the Exalted, the strong, the heroes of society.The people he was supposed to praise were the ones who took his last hope in life away before killing Adam as well.So, when he regressed with a villain system that rewarded him for killing Exalted...[First Exalted killed!][Artifact: The Mantle has upgraded to level 2!]

The protagonist of a war fantasy novel, Theo, competes with his rival and antagonist, Luke, for the position of Supreme Commander. Having been reincarnated into Luke’s role, he struggles to fulfill his duties as the villain. “It seems like principles as a soldier, the duties I should uphold, don’t matter to you at all.” Even if misunderstood by Theo, Luke silently remained faithful to his role as the antagonist. After completing all his duties, Luke successfully gave Theo his happy ending, cast aside his military uniform, and retired from the army. Now, Luke planned to create his own future story without interference from anyone. That was the plan, at least… “Why go this far? I’m no longer a soldier, and if you really think about it, we were never on good terms anyway.” To make matters worse, not only had he unexpectedly reunited with Theo, but now, Theo was persistently and seriously pressing him in a way he hadn’t imagined. “I want to know you better.” It was a completely incomprehensible statement, and it wasn’t even an appropriate answer to the question. The protagonist came to the antagonist and suddenly asked for help, simply because they wanted to know him better?

This book is about baby-making.