フォルテシモBELL is a solo character song for 天王洲 なずな (Nazuna Tennouzu), a member of the fictional music unit イロドリミドリ (Irodorimidori) from SEGA's rhythm game universe. The track was composed and arranged by Junpei Fujita of Elements Garden, with lyrics by Izumi Arisato and vocals by Ayano Yamamoto (credited as Nazuna's voice actress). The music video was created by 鑓田 (alpha complex). First appearing in CHUNITHM in November 2015, フォルテシモBELL joined the maimai song library on February 7, 2017, as part of the MURASAKi version under the オンゲキ＆CHUNITHM genre category. The song's title fuses the Italian musical term "fortissimo" (very loud) with "BELL," evoking a bright, resonant quality that matches its lyrical theme, a gentle school-life narrative about pursuing dreams, climbing toward the stage, and carrying hope through music. Over successive maimai updates, its chart levels have been revised multiple times; by the BUDDiES+ era, the Expert chart settled at level 9 and the Master chart at 12+ (constant 12.6), making it a solid mid-tier challenge. The MASTER chart, designed by ロシェ@ペンギン, is known for its note density leaning heavily toward Slide notes (92 of 595 total), while the Expert chart was crafted by 玉子豆腐.