Obtaining 10x rewards! Reincarnated into a novel as a side-character! - Chapter 261: Her curiosity!

A story about a traveler who crossed into a parallel universe, relying on his Proficiency ability to continuously grind experience and become stronger.

[Warning! The MC here is the literal incarnation of evil and madness throughout the story.]Valtar Titanblood formerly known as Ethan Martin on Earth was struck by an unimaginable tragedy and took his own life at the end, his whole life filled with misery and incompetence of his own doing.Then he transmigrates to a world of infinite proportions and power that defies logic, this new world which is filled with Dragons, Titans, Ouroboros, and countless more bloodline creatures and mythical beings, also powerful humans who are known as Mystic roams here as well.Valtar in this new world has the Karma System and the bloodline of an unknown titan running through his veins, with these powers in hand he who was supposed to become the symbol of justice and equality decided to become the paragon of madness and evil.He who had the tools to become the Judge of Truth and the figure of Respect chose to become the arbiter of chaos and the embodiment of fear.

Leon transmigrated and became a lab rat for Hydra. But he ended up awakening the sign-in system.[Ding, sign-in reward: Glint-Glint Fruit(Pika Pika no Mi).]He starts by destroying the Hydra Base.He accumulated some time and got himself another reward![Ding! Get the sign-in reward: Sun Breathing Technique.]

A 13-year-old deaf teenager living in the 21st century suddenly found himself as a young boy in Japan during the early 1900s. With two World Wars, two nuclear bombs, Hitler and many other disasters awaiting his future, he thought things couldn't get worse.Except it did.He found out later on that he had actually reincarnated into the world of Demon Slayer where man-eating demons ruled the night. He thought things couldn't get worse.Except it did.But hey! At least he had unparalleled talent, incredibly special eyes and future knowledge.How will the story of Demon Slayer change with the addition of this unique character? Will so many still die if the Hashiras had one more pillar in the final battle?Or will the story end on a much happier note?