Statement #1: Some anime are good anime.
Inference: Some anime are NOT good anime.
Statement #2: Some anime OPs are in Engrish.
Statement #3: Good anime's OPs are Engrish
NOT true: Not all anime with Engrish OPs are good.
The CONVERSE (All Engrish OPs are from good anime) is not necessarily true unless it's proven that's it's true both ways, while the CONTRAPOSITIVE (Anime with non-Engrish OPs are not good anime) is always true given that the statements given are 100% true.
/a/ - Philosophy and Logic.