Board Thread:Episode Discussions/@comment-25319479-20170426101051/@comment-25122992-20170426173236

Well, this creature has seemingly been connected to Boruto before, that could be the reason why it influenced only the persons who were close to him like Denki, and the summoning just established the connection as well, since I don't think that any of the contract scrolls stored in Academy could include such a monstrous and powerful being, it would be the same as to keep a contract with Baku (Danzo's chimera) in Academy.