During their martial arts training expedition in China, Ranma Saotome and his father Genma suffered an accident, which in turn, afflicted them with a curse—whenever they are doused with cold water, Ranma transforms into a girl, while his father turns into a panda! Only hot water can reverse these changes, but any further contact with cold water opens the can of worms once more. Unfortunately, the trouble does not end there, as Ranma finds out about his betrothal to one of the daughters of Soun Tendou, his father's closest friend. During the families' first meeting, it is decided that Ranma is to be married to Akane, the youngest daughter, a decision that is met with vehement protests from both sides. The two are simply not compatible, yet they are forced to live under one roof. Ranma's status quo further adds to the chaos, leading him to a series of comedic situations and misunderstandings that, in the grand scheme of things, may just be what he needs to work with Akane.

Eiji Kitahama, a second year high school student, just wants to be popular. To help him realize this dream, Rin Nanakura, his junior in the drama club, uses her acting skills to create a harem of loving girls for him. Though the various "girls" all show fondness toward Eiji, the affection of the actress behind them is very real. Rin's colorful acting continuously delights Eiji, but will the starlet herself ever make her way into his heart?

In a time when the great war between five rival races for supremacy on Earth ended with humanity's victory led by the hero Sid, the world suddenly gets "overwritten" right before the eyes of a boy named Kai. In this rewritten world, Kai witnesses humanity's defeat in the war as a result of Sid's absence—where dragons and demons now rule the land, and Kai himself has become a forgotten existence to all humans. However, after encountering the mysterious girl Rinne, Kai resolves to break free from this rewritten fate. In a world without a hero, he inherits the sword and martial skills of the hero (Sid) and challenges the powerful enemy races that dominate the land.

Under the tutelage of the great demon warlock Romberg, Ike grew up with knowledge regarding an ancient advanced civilization that once ruled the land. Coupled with his innate talent in magical arts, this upbringing allows Ike to quickly rise in the Demon Lord's army ranks, leading his brigade to consecutive victories against humans. However, Ike has a secret—he is a human himself. Despite knowing all too well the consequences if this information is ever to leak, Ike is willing to face such immense danger to achieve his goal: find a way for humans and demons to coexist and stop the war that has been carried on for far too long.