The Yu Brother's Case Book - Volume 1 Chapter 7.1

Just like how everyone adored heroes in their childhood, a certain young man adored those powers hidden in shadows. After hiding his strength and living the mediocre life of a mob character by day while undergoing frenzied training by night, he finally reincarnates into a different world and gains ultimate power. The young man who is only playing at being a power in the shadows, his misunderstanding subordinates, and a giant organization in the shadows that gets trampled…. This is the story of a young boy who had adored powers in shadows possibly eventually reigning over the world of shadows in another world.

Princess Leah wrote a suicide note ahead of her wedding.

Takebayashi Ryouma, a 39 years old man with hidden past, found himself in a strange white room. The gods tell him that he has died and that they are sending his soul to a different world, a world where magic exists. After living alone for 3 years, his gamer soul loses its common sense and starts along crazy routes.

A side story series featuring the girls of Kyoukai Senjou no Horizon.