In modern Japan, high schooler Rekka Hanabishi struggles with the ninja legacy until he saves Yanagi Sakoshita from trouble. Impressed, Rekka pledges to be Yanagi's protector, leading to a bond where they share their extraordinary abilities: Yanagi's healing powers and Rekka's fire manipulation. However, their newfound connection attracts the attention of the enigmatic Kage Houshi, who threatens them, revealing a dangerous past. Despite a brief standoff, Kage Houshi withdraws, leaving Rekka and Yanagi to resume their routines, unaware of the perilous ninja world awaiting them.