New York Arc

The New York Arc is an anime original arc spanning 13 episodes (from episode 66 to episode 79, with an unrelated episode airing after, and a clip show episode recapping the arc after that). The arc sees Sana and Naozumi (along with their managers), travel to New York to perform in a play, which also leads to Naozumi learning about his parentage.

This arc is not canon to the manga's continuity, and was presumably put in the anime as a buffer, allowing more manga chapters to be written.