For the translator, the "DEEEH" are likely to be from "DEKKE" meaning "HUUUUGE", this could be either her height or her ass in the context.
So the proper translation would be something like "HUUU-" or "BIIII-" from "Huge" or "Beeg" :x
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Maniana saying "that" was the last time, but according to Demonio himself, weren't there some "training" sessions in his training montage before school started?
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Seems like the new milf may be a mini giantess (yay), but then you gotta wonder, in the last chapter, she was sitting in a forest with reasonably sized small birds. Should we understand those small birds were the size of hawks or something?