I am a member of Daigo's niko-niko channel, and there is a story that reminds me of my childhood memory at preschool. Daigo takes a cold shower to boost immunity and in his book he says it is a bathing way of ancient Rome. When I was little I had the moment I was always wishing to avoid after bath at nursery school. The teachers would pour cold water over me, I think other kids too, and it was so cold but at the same time I knew the body would get hotter soon. I only had to wait until my skin started to heat up. I wonder if they were giving me the ancient Rome style knowingly, but at least I believe they had known the effect and I'm glad that Daigo has done the same thing! I want to tell him I was doing it nearly 30 years ago!