Testosterone is a hormone that supports masculinity. It is believed that the more testosterone you have, the more popular you are from the opposite sex. A large study of Americans also reports that men with high testosterone levels tend to have more partners in their lives and are more likely to get married multiple times. Testosterone is important for men, but its amount peaks around the age of 20 and decreases with age. The causes are a decrease in the substance called "GnRH" that commands testosterone production, and a decrease in the number of Leydig cells that produce testosterone. It is known that a decrease in testosterone causes various symptoms in both the mind and body. So this is the male version of menopause. There are many ways to increase testosterone, but hospitals have "testosterone replacement therapy." As a general rule, hCG hormone is injected once or twice a week. Androgen replacement therapy by injection is performed for about 3 months to see the effect. If it is effective, we will continue replacement therapy for about one year. It hurts, is expensive, and requires frequent injections to be effective. The most scary thing is that once you start a hormone injection, you can't stop it. If the body doesn't have to make that hormone anymore, it won't try to make it anymore. Since it is Western medicine, it may have a momentary effect. To increase testosterone, you can sometimes take Japkasai, and the effect may vary from person to person, so please make your own judgment.