Luna Kusakari possesses shoulder-length white hair styled with left-sided bangs and blue eyes. Her surname, Kusakari (草刈), fuses the Japanese words for "grass, herb, weed" (草) and "mowing, reap, cut, clip, trim, prune" (刈). She bears the epithet "他者を寄せつけない孤高の実力者," meaning "a solitary powerhouse who doesn't let others approach."

Driven by a desire to join her sister's school, Luna dedicates herself to baseball excellence. This pursuit leads to an encounter with unexpected words that challenge her path. Her story converges with Yuzu Takanashi, who played baseball from childhood until reaching her perceived limits in Little Senior League, resulting in middle school uncertainty. A pivotal event involving a white ball brings Luna and Yuzu together as both contemplate their futures. This meeting significantly influences their decisions and marks a key point in Luna's development.