Emerald Serenade

The Emerald Serenade (エメラルドセレナーデ) is an Emblem Heartless from Kingdom Hearts 358/2 Days. It is a member of a large family of Magic Heartless, whose names reflect their body color and a music-associated word. The Emerald Serenade, although doesn't attack you will summon many other heartless to do so instead. They are mostly green except their bodies are striped in a repeated green and white pattern. As you fight one they move along the same basic path over and over making it difficult to catch. This means following it would be a waste of time.

Kingdom Hearts 358/2 Days
These large flying Heartless travel along a set path, making ambush a useful tactic.

Their speed grows faster as their HP drops, rendering them increasingly tricky to finish off.