The Icha Icha Series

Meikyō pointed out several relatively serious hidden injuries on Might Duy's body one by one. Some of them had been caused by Might Duy's less-than-ideal training methods when he was young, while others resulted from excessive training combined with insufficient nutritional supplementation. Perhaps it was precisely because Might Duy had taken those detours himself, and had made sure to supplement his son's nutrition while he was young, that Might Guy had been able to reach his proper physical peak in perfect health.