Many fans are confused when watching Overlord and Ainz Ooal Gown glows green. Why does he do that Did he eat kryptonite? Is it a superpower? Does he have indigestion? The answer may surprise you.
Ainz Glows Green whenever he feels intense emotion. It’s an emotion suppression system. The reason this system is in place is because Ainz is Undead. And Undead are NOT supposed to feel emotion. It’s the way for this “game” to feel as real as possible. Although, he isn’t in a game anymore, is he?
Not only does the emotion suppression make this world feel more accurate, but it’s also built in to Ainz’s abilities and functions as a passive skill. Ainz Ooal Gown is a Skeleton Mage, Elder Litch, and a member of the Overlord race. Being such gives him the advantage of a mind not tethered to human emotions.
Other beings, such as Albedo, can feel intense emotion. And this may cloud their judgement.
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Can Ainz Feel Emotions in Overlord?

Yes. This ability doesn’t mean Ainz can’t feel emotion. He certainly does. But, whenever a strong feeling passes over him, the emotion suppression kicks in so he is able to think with a clear mind. Wouldn’t it be great if we could all do this from time to time?
As the show progresses, Ainz begins to wonder how much of his humanity is left? Is he still a human stuck in another world? Or has he truly become an Undead being?
Read More: Can Ainz Turn Human?