君の知らない物語 (Kimi no Shiranai Monogatari) is a defining J-pop ballad that served as the ending theme for the 2009 anime series Bakemonogatari. Composed, arranged, and penned by ryo, and sung by nagi under the supercell name, the song pairs a gentle yet driving instrumental with lyrics that use the Summer Triangle constellation, Deneb, Altair, Vega, as a symbol for unspoken romantic feelings. It was released as a single in August 2009 and later collected on supercell's second album Today Is A Beautiful Day. The song entered maimai with the launch of maimai GreeN on July 11, 2013. At the time, it was the only master-licensed track (i.e., an original recording, not a cover) in the ANIME category, reflecting a direct licensing agreement between Sega and Sony Music. The original Standard charts span Basic 2 to Master 11+ (level constant 11.6), with Expert chart design by はっぴー and Master chart design by 某S氏. In 2020, the song received a full set of DX charts, Basic 3 through Master 12, which added Touch notes and higher total note counts. These DX charts debuted in the International (Asian) version of maimai でらっくす PLUS before arriving in Japanese cabinets on July 31 of the same year, a release-order anomaly that was shared only with コネクト at the time. Although licensing changes led to the song's removal from Chinese and Asian English cabinets (舞萌DX 2023 and maimai DX BUDDiES onward, respectively) and its delisting in Japan on March 21, 2024, 君の知らない物語 remains a nostalgic highlight for players who experienced the GreeN era and a lasting favorite among fans of anime-themed rhythm game content.