So, the tragedy just happened...
You see, Double Leaf knew Hei Fan as a "median-level hacker," and earlier on even used this to turn the tables on Double Leaf once. Since then, the girl, utterly oblivious to the severe bug in The Realm of Innocence, was led further and further astray, making the likelihood of her catching Mo Tan in real life infinitely close to zero.
In Double Leaf's mind, she had become aware that BLACK had noticed her investigation of "Mo Tan," and had even been misled by them. To further sow confusion, in The Realm of Innocence, they even deliberately chose a nickname very similar to "Mo Tan," "Tan Mo," clearly trying to pass the buck and play tricks. Unforeseen by him, however, was that the very character "Hei Fan" belonging to Mo Tan had already befriended Double Leaf before he could pretend to be Mo Tan and trick her. This completely foiled BLACK's despicable plan, a cause for celebration indeed, a cause for celebration indeed.