In This Life, The Greatest Star In The Universe - Chapter 77:

Rogel downloaded a magical pixel game—“Mysterious Sea”.After manifesting the kitten from the game, he fell into contemplation...

The male student, Fukai Nagamasa, ignores his studies for college entrance exams in favor of following the path to chuunibyou. As he fainted during night cramming session before the exams, he realized that he was transported to a parallel world as a feudal lord in the Sengoku Era. Not to mention that suddenly, he was marrying the sixth Demon King, Oda Nobunaga’s little sister, the one who was purported to be an unrivaled beauty?

Orion was on his way back home from work.He was hurrying back home to take a nap while planning how he would spend his weekend as well, but while he was lost in thought, a truck suddenly appeared out of nowhere and the last thing he remembered was the truck barreling towards him before everything around him turned dark.However to his surprise, he didn’t feel any pain after having the accident. In fact, he couldn’t see anything.Everything around him seemed dark but when he opened his mouth to speak, he heard the gurgling sounds of a baby.Noticing that the one sounding like a baby was him, Orion tried to open his eyes to know exactly where he was, but when he did, the first thing his eyes fell upon was a stunning beautiful elf, holding him with the most tenderest of care.Not only was she his mother, she was also a queen as well and she had a beautiful sister who adored him just as much as his mother.Aside from this, Orion also noticed he had received a system which allowed him to grow and evolve faster than a normal High Elf but after finding out the huge role his mother played in eradicating the war between all races, Orion vowed to live a happy and fulfilling life with his mother, aunt and a few others he cared a lot about.

Imagine being forced to live, after death, as incorporeal bodies trapped in a vast space of nothingness for thousands of years, with nothing to do but exchanging past memories with other cohabitants (read: weirdos). Everybody wanted out, but there was no way to leave the Void…

Until one day, a young man was finally summoned, as a powerful but reluctant mentor, by a bubbly and motivated but completely naive young girl. Baiyi, finally out of the Void, was the only one who could save all of the other 32 souls from their prison and his summoner might just be The Key to their freedom.

However, Baiyi had to use the techniques and abilities the other souls had taught him throughout the years, and together with his own extensive knowledge of anime and game tropes from his shady and dangerous past as an otaku, to face the biggest challenge of them all: training the clumsy young girl he was forced to partner up with… into a competent sorcerer!

This is a story of heroic adventures, cunning strategies and romantic tales. How will our MC thrive in a world completely strange to him? Where will his ambitions and abilities take him in the palace?

- Description from Novelupdates