Hōsuke Sharaku is a junior high school student with a third eye on his forehead, usually hidden beneath a cross-shaped bandage. This bandage suppresses his true nature as the last descendant of an ancient three-eyed civilization that built wonders of the ancient world. With the bandage secured, he displays a naive, clumsy, and childlike personality, making him vulnerable to bullying. Removing the bandage activates his third eye, unleashing formidable psychic powers, advanced intellect, and a malevolent alter ego determined to dominate the world. In this state, he commands ancient technologies and can summon a weapon called the Red Condor. His dual personalities retain no memory of each other; the bandaged Sharaku remains unaware of his actions when the third eye is exposed.

His biological mother, also three-eyed, entrusted him as an infant to Dr. Kenmochi before perishing in a lightning strike. Dr. Kenmochi applied the bandage upon noticing Sharaku’s developing third eye and associated evil behavior, seeking to protect humanity. Sharaku investigates global ruins linked to his ancestors, such as those on Easter Island, in Mexico, and in Arizona, deciphering ancient scripts to uncover his heritage. His classmate Chiyoko Wato frequently accompanies him, serving as his protector, confidante, and moral counterbalance. She is one of the few individuals he trusts in both states and often intervenes to stop his destructive plans.

Appearing across Osamu Tezuka’s "Star System," Sharaku's character retains his core dichotomy in other narratives. In *Astro Boy: Omega Factor*, his unsealed third eye manifests as the prince of the Mu Empire, deploying an orbital weapon called the Death Mask to eradicate robots. After defeat, Wato bandages his eye, restoring his docility. In the 2003 *Astro Boy* series, he searches for his missing mother (reimagined as Dr. Wato) using a magnetic orb device. The *Black Jack* anime depicts him as a normal student with a crush on Pinoko, while Wato acts as his older sister.

The 1985 special *The Prince of Devil Island* adapts an "Easter Island: Sea Voyage" arc, where Sharaku and Wato explore a mysterious ship leading to adventures on strange islands, emphasizing entertainment while maintaining Sharaku’s role in deciphering ancient mysteries of his lineage. His character design, including the military-style school uniform, reflects Tezuka’s own childhood experiences with bullying and fascination with ancient phenomena.