"Knights of Ramune & EX" is a two-part OVA series that blends science fiction, fantasy, and comedic elements. The story is set in a futuristic universe where the galaxy is protected by the Ramune Knights, a group of intergalactic defenders. The narrative centers on Cacao, a young boy who becomes the chosen protector of the galaxy after inheriting the powerful Ramune Bottle, a mystical artifact that grants him extraordinary abilities. Alongside his companions, Cacao embarks on a mission to safeguard the galaxy from various threats, including the malevolent Dark Joker and his forces.

The first OVA, "Knights of Ramune," introduces Cacao and his allies as they confront Dark Joker, who seeks to conquer the galaxy by harnessing the power of the Ramune Bottle. Cacao’s journey is marked by battles, comedic mishaps, and moments of self-discovery as he learns to wield his newfound powers. The second OVA, "Knights of Ramune EX," continues the story with a new threat: the evil organization known as the Dark Joker Corps. This installment delves deeper into the characters’ dynamics and expands on the galactic conflict, with Cacao and his friends facing greater challenges and adversaries.

The series features a mix of action, humor, and lighthearted moments, with a focus on the camaraderie between Cacao and his diverse group of allies. Key characters include Cacao’s loyal friends, such as the spirited and resourceful Milk, the stoic and skilled Vanilla, and the enigmatic and powerful Princess Ramune. The antagonists, led by Dark Joker, provide a counterbalance to the heroes, with their schemes and confrontations driving much of the plot. The narrative explores themes of heroism, friendship, and the struggle between good and evil, all set against a backdrop of vibrant and imaginative galactic settings. The series’ episodic structure allows for a variety of adventures, each contributing to the overarching storyline while maintaining a balance of action and humor.