Yes, you are absolutely allowed to bring luggage on the Tokyo Monorail, and it is specifically designed to accommodate travelers going to and from Haneda Airport (HND). Unlike some standard Tokyo subway cars which can be very cramped, the Tokyo Monorail cars feature dedicated luggage racks and extra-wide vestibules to make traveling with large suitcases much easier. There is no additional fee for bringing bags, and the service is included in the Japan Rail Pass (JR Pass) if you are using the monorail from Hamamatsucho Station. For passengers with exceptionally heavy or numerous bags, the monorail stations are equipped with elevators and escalators for step-free access from the platform to the airport check-in counters. However, if you are traveling during the morning or evening rush hour (typically 7:30–9:00 AM and 5:30–7:00 PM), the trains can become extremely crowded with local commuters. During these times, it is considered polite to keep your luggage as close to you as possible and avoid blocking the doors. If you have more than two large suitcases per person, you might consider using a "Luggagent" or "Hands-Free Travel" delivery service at the airport to have your bags sent directly to your hotel.