I Pioneered Scientific Magic - Chapter 549: The Prelude to the War of Planes

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

A recurring nightmare afflicted Khan's nights since the Second Impact. His dreams replayed the scenes of the crash of the Nak's spaceship, an alien race that the humans had defeated five hundred years ago.

Hello, my name is Hespera, and I am a psychopath or at least that is what all my doctors kept saying... and the god of reincarnation. He and the primordial of Chaos were quite the amusing duo. Oh, did I mention that I am also the first (and last) family member of Chaos. Yeah, that surprised me too. Apparently becoming a Blessed isn't easy.Anyway, I'm about to head out to my... hmm, fifth world? Or was it the sixth? Oh drat, I lost count! Well, whatever. It was lovely meeting you strange person from behind the screen. Please enjoy my life as-Girls! Stop groping me~

Our straight (?) bottom woke up ten years into the future and found himself on the bed of his childhood friend… At the start, the bottom was shocked to his very bones, but he soon quickly accepted this premise and found the whole situation to be rather amusing. Precisely then, the bottom once again went back to his timeline — back to when he and the top were just platonic childhood friends.

Landmines include but are not limited to: Sweet & naive bottom, a president story, logic is dead, slow-progressing romance, the protagonist’s name has too many character strokes, the names are hard to pronounce, too many gay characters…

- Description from novelupdates