If they scanned using their Spiritual sense they might've been able to tell but no one did. Even if someone finds out about Fenrir Vishnu isn't too much worried. With his talent, he is allowed to have such a beast by his side. If it was some no-name who obtained such treasure he'll be killed and his treasure will be then looted. You need to have a certain level of power or status to have good things otherwise other people will snatch them from you.
When the night came Vishnu went downstairs to have dinner at the cafeteria of the inn. It was bustling with people. Vishnu was wearing normal clothes and wasn't releasing his aura so nobody paid him any attention. He took his food and went to the corner of the hall to have dinner alone. As he ate he listened to people's gossip. Yes, he is here to hear gossip. As he didn't leave he wants to know what happened during today's test otherwise he could have just gotten his food served to his room.
