I have no idea what EĐ is. Some random Touhou 嫉妬, I guess.

Embodiment of the scarlet Devil, perhaps.

Interesting book there, Patchouli.

I am the Queen of Erectile Dysfunction, you ignorant wench.

なっなんて恐ろしい力！

O
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s
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i
t
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I wonder what other interesting books that library has.

Doesn't EĐ simply refer to ending? Patchy only shows up in the ending scenes despite not appearing at all in most of the games after TH06.

Best English Ever

I loved the reverse translation on the last panel :P