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Another point. I’m not sure if it is correct, but I will use the term “body awareness”. There are several levels or layers of body awareness. From a toddler level:”Hey, I have a foot and I can take it in my mouth!” to a high level of advanced yoga practitioners, who can sit in a pool and suck the water inside their bowels.
This manga touches the sensual, erotic layer. Kids begin to investigate their body while still being in the womb, and naturally progress further, but as soon as they get to their genitalia come the parents with:”Do not touch THIS! IT is dirty”. Or something similar. Oh-oh… “Houston, we have a problem”.
Kids must learn how to deal with their own private parts and how to use them for pleasure (but without active help from adults!). One of the consequences of lacking this experience is shown in the manga. “The body betrays me!!!” How is this possible? Well, you ignored your own body for years, now it ignores you :D
It’s valid not only for erotic/sexual experience but for mental and physical exhaustion. If you work too much, you’ll get the burn-out syndrome, if you train too much, something will break to give the body some time to relax and rest.
And, strangely enough, bondage can help to solve this psychological puzzle. We (our mind) do not allow our body to enjoy some primitive (from our overly educated point off view) actions and reactions, but when we are bound…. Mmmm… there is nothing we can do about it, right?