Date Boo Masamune, a French Bulldog bearing the reincarnated soul of the legendary warlord Date Masamune, retains both his ancestral memories and unyielding demeanor. His compact frame sports short white fur accented by deep charcoal patches along his back, a crescent-shaped mark beneath his neck, and a stark black blotch over his right eye—a canine echo of his historic eyepatch. Upright ears with pink interiors crown his proportionally large head, while small paws and a stubby tail complete his stout silhouette.

Pride anchors his personality, manifesting in grandiose declarations of his former title, the "One-Eyed Dragon of Ōshu," and sharp critiques of modern media’s misrepresentation of his rivalry with Sanada Yukimura. Despite this, he navigates contemporary life with adaptable ease, embracing pop culture and leisure comforts. His owner, unknowingly housing a historical icon, nicknamed him "Boo" due to a fascination with samurai-era lore—a title he disdainfully tolerates.

Encounters with fellow reincarnated warlords reignite old tensions, particularly with Yukimura, whose present-day canine persona diverges unexpectedly from their storied past. Pragmatic yet optimistic, he balances appreciation for modern conveniences with disdain for oversimplified historical narratives. His arc grapples with merging his warrior identity with the trivialities of pet life, though specifics of this evolution remain broadly outlined.

No extended media adaptations, such as films or spin-offs, are presently noted.