forte_(symbol)
A dynamic notation used in written music, which denotes a dynamic or volume of "loud" and is typically depicted in a cursive "f".
Tachibana Hibiki (Senki Zesshou Symphogear) has a forte-shaped scar on her chest, and Kougami Kanon and Kunieda Shiho each wear a forte-shaped hairclip in their hair.
Not to be confused with fortissimo, which features two "f"s.