Since the night was getting late and White Mist didn't want everyone to exhaust themselves traveling back to their accommodations (he wasn't aware of Emma's superpower which allowed everyone to travel everywhere they want without difficulty) he decided to book a couple of suites for everyone. As one of the top ten superheroes, booking a room for a couple of days in the Grand Hotel was petty cash for him. That's why he didn't mind it at all.
After dinner, Satoshi and the others were about to head out to return to their respective places when White Mist told them to stay. Of course, they couldn't reject his invitation since he had already booked some rooms for them. The Grand Hotel is one of the world's most prestigious hotels, so the invitation was always welcome. Even Jack Michael who never bothered with any of White Mist's invitations in the past decided to accept his invitation this time.