Akuyaila

 is a xenogender related to being a villain, but secretly being kind and good.

Etymology
While etymology is not specified in the original coining post, it is assumed that the aku segment of the word comes from the Japanese aku no, meaning evil and referencing the villainous nature of the gender.

Definitions

 * a gender connected to being a villain, yet being secretly kind-hearted and mostly morally good. - cinnamogai, 2021