I've been recieving emails about issues regarding Tien and Yamcha. Well though it never actually is stated in the manga or anime Tien iss in fact an alien and I intended for him and Yamcha to learn Kaioken. In the final version of the manga this doesn't occur as I decided to make Goku the only one to do so. It's what sets him apart from the others. He's always one step ahead. It is up to all of you to decide whether or not you consider this canon or not as it is only my original intention. I hope this helps settle this argument. Akira Toriyama