B-Bump Akihabara

This climbing gym has daily lessons for beginners who'd like to learn more about bouldering or rope climbing, and also features training sessions for first-timers and children. It's a great place to find new climbing buddies - no reservations are required, and all classes are free of charge (except for registration and entrance fees). Finally, the blacklight-decorated 'Space Wall' will remind you that you're still in Akihabara after all. The same company also operates a gym in Ogikubo.