Well, it didn't. I have still no idea why Bob keeps attacking them, and he seems reluctant to tell the reason. Perhaps Bob has the box and he's somehow using it to boost his powers (or intends to), and that's the reason why he doesn't want the search party messing around on Earth. Well, that's the only reason I can imagine, unless there's something far more stupid he's hiding, like some past misdeed. Otherwise I can't imagine why he would be concerned about somebody like Yuri and his few buddies.

But I gotta say Yuri's mom is the best character in this series.