DxD: Scion of Lucifuge - Chapter 1: The Boy Who Refused to Be Left Behind

After transmigrating into a beast world, Rong Mingshi discovered that the people of this world experienced widespread mania. For example, when their emotions were abnormally agitated, they would become destructive beasts. If their emotions were abnormally low, they would shrink into their young beast form.

When Ye Mo suddenly woke up, he realized that everything around him seemed to have changed: He has been transmigrated into the modern Earth where spiritual energy is scarce. His pretty master from his former world was nowhere to be seen. Most importantly, he found himself in the body of a young man who has been abandoned by his clan for an embarrassing reason…

- Description from Novelupdates

In a world where magic intertwines with reality, a dying human girl named Elara awakens to find herself in a foreign land. The air smells of ancient forests, and the sky is painted with hues she’s never seen before. Before her stands the enigmatic Demon Queen, Seraphina, her eyes as cold as the ice that encases her throne.Seraphina proposes a desperate bargain: a contractual marriage between them. In exchange for Elara’s hand, Seraphina promises to save the crumbling human kingdom from impending doom. Elara, with nothing left to lose, accepts, thrust into a web of intrigue, danger, and forbidden emotions.As they embark on their perilous adventure, Elara discovers that Seraphina’s icy demeanor hides a tragic past. The Demon Queen’s power is unmatched, her wrath swift and merciless. Yet, beneath the frost, Elara glimpses vulnerability—a longing for connection that defies her ruthless reputation.