Douluo Continent: I came from Demon Slayer!

[A fanfiction featuring multiple female protagonists, no system, a genius protagonist, and swordsmanship growth] Lin Yang transmigrates to the Demon Slayer world, joins the Demon Slayer Corps, and with the help of his companions, drags Muzan to sunbathe, achieving a "perfect" accomplishment. However, he then transmigrates again to the Douluo Continent world, beginning his third life. At six years old, he awakens twin martial souls. One hand wields a Nichirin Blade, the other holds demon blood—so, as the Sun Pillar, am I the Demon King? The Nichirin Blade stacks amplifying spirit rings, making even a basic attack a powerful move! The Demon Blood Martial Soul grows with his spirit power level, generating its own spirit rings and awakening powerful Blood Demon Arts! There are also breathing techniques, the Transparent World... bringing a tiny, yet significant, shock to the spirit masters of the Douluo Continent. He slays demons and monsters with his swordsmanship, and with the blood of the Demon King, he steps into the realm of gods.