TV-Series
Description
Harunobu Nikaidou is a professional shogi player who declares himself the best friend and lifelong rival of Rei Kiriyama. Their competitive bond started in childhood shogi tournaments and persists into their professional careers, with Nikaidou persistently challenging Rei despite frequent losses and viewing their connection as deeply significant.

He possesses a short, chubby build, standing 152 centimeters tall, with straight brown hair and black eyes. His complexion is often pale and flushed. He typically wears polo shirts with slacks or button-down shirts paired with sweater vests, adding coats in colder weather and suits for formal shogi events.

Born into a wealthy, distinguished family, Nikaidou contends with significant health challenges from an incurable chronic kidney disease present since childhood. This condition contributes to his portly physique and requires constant medical supervision. His butler, Hanaoka, accompanies him at all times to manage his health needs. While some observe his physical frailty, the full extent of his illness remains confidential at his request, known only to Rei, their mentor Kai Shimada, and the shogi association chairman.

Nikaidou exhibits an earnest, cheerful, and resilient personality. He approaches shogi and life with persistent determination, refusing to let his illness diminish his ambitions. He becomes emotional after losses, often crying privately, but maintains strong public composure and quickly resumes training. His stubbornness manifests in refusing to concede defeat easily and insisting on continuing matches even when visibly unwell.

As a shogi player, Nikaidou holds the rank of 4-dan in Class C2 at the series' beginning, later advancing to 5-dan in Class C1. He is a junior disciple of Kai Shimada and part of Shimada's study group. His preferred strategy involves static rook positions, specifically the Static Rook Anaguma formation, reflecting his deliberate and tenacious playing style.

Key moments highlight his physical struggles during matches, particularly in hot conditions which exacerbate his health issues. During one childhood tournament, he persisted through visible discomfort against Rei, sweating heavily on a sweltering day before ultimately losing and crying afterward. Similar scenarios occur in their adult matches, where he plays Rei intensely into the evening despite declining physical condition, demonstrating his refusal to yield.

Nikaidou is modeled after the late real-life shogi prodigy Satoshi Murayama, sharing parallels as talented players confronting serious health challenges. His family background and illness shape his worldview, but he channels this into shogi as his central focus. His relationship with Rei evolves beyond rivalry into mutual respect, with Nikaidou serving as an emotional motivator who openly admires Rei's dedication.