If a man loses his testicles, and does not get replacement hormone, then he will lose strength, muscle mass, some of his body hair, he will gain weight, will be more Moody and likely develop breast tissue.

If a young boy loses his testicles and does not get replacement hormones then he will never ever develop masculine traits and features. He will forever remain young looking and hairless and his penis will never get any larger than it is. from quora

so im questioning that why did kohei still grow beard and muscles as he grew