He's Playing Our Song(「彼が奏でるふたりの調べ」)

Tamami (Hana Kuroki) is stuck in her job and life. One day, she hears a song from her youth and her mind goes back 15 years. In high school, the reserved Tamami meets Rin (Masataka Kubota), who plays the piano. Through their shared love of music the two become friends, but drift apart. Now in her thirties, she discovers that Rin has become a musician when she posts a picture on social media.