Karasu Tengu is the main antagonist of Precure Dream Stars!. He's an evil Demon who took over Sakura's world of Sakuragahara to steal all the beautiful things for himself. He has mind control abilities and views Sakura and the Precures as a threat

When they exit the door of light, there lies a sparkling and glittering mysterious world. And there, they meet a lone young girl. What will happen to the Precures in this world enveloped by cherry blossom trees in full bloom!? This spring, it's not an All Stars, but a completely new story that is beginning. 
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(Source: Anime News Network)