In the Multiverse as an Demon Overlord

Samuel was your typical teenager. He studied for school, socialized with friends, etc. However, this was about to change on one special day after he saw something he shouldn't have. As a result, a contract killer was set on him, which he was fortunately able to knock out due to his prior knowledge of martial arts and spear arts. Inexperienced as he was, he only knocked out the assassin, which would cost him his life ultimately. When he had already accepted his death, he found himself in a new world as a half-demon. Equipped with a system, he sets out on a journey through the multiverse to conquer as many worlds as possible, and let his name roam the stars. +++ Of course this book doesn't contain NTR or YURI,