Chiba's Kamogawa Seaworld aquarium celebrates the holidays with extended opening hours between December 20 and 24, with visitors entering the park after 3pm paying only ¥1,000 per head. In addition, a special killer whale show will take place at 5.30pm every day during the event period. If you're looking to go all-out, book a spot for the Christmas Night Stay on December 20: a small group will be allowed to stay in the park overnight, taking a behind-the-scenes tour of the facilities and having an evening meal before bedding down in front of a floor-to-ceiling fish tank. Places are limited to 20 people – call 04 7093 4803 (Japanese only) for reservations. The rate is ¥15,000 and you need to bring a sleeping bag with you.