Ache

Aches are blue bats resembling Keese found in Zelda II: The Adventure of Link, usually dwelling in caves or forests, hanging upside-down. When Link approaches one, it quickly swoops down before arcing back up to the ceiling. If Link is still nearby, it will continue to do this consecutively until he gets far enough away or defeats it. They are extremely weak, taking only a single hit to defeat. A red, transforming version of Ache, called Acheman, also appears.

Aside from the wild Aches, some Aches work for Ganon and are disguised as town folk, referred to by others as "eyes of Ganon." When Link speaks to one of these, it transforms back and starts attacking. Due to the lack of ceiling, they hang from thin air. Additionally, due to the game's "blue" palette being assigned purple and tan values in towns for town folk, they appear as such.

Manual comment
"A bat that lives in dark places. Usually, it hangs upside down from trees or in caves."