There are several parts that can be an option for intimacy guiding. Mucous membranes are located in the throat, nose, mouth, urethra, rectum and also the vagina for women. Of the many options, Kai knew which one would be more effective in bringing down the heat inside Noah, but then again, it was risky. He didn't want to do something that would get him into trouble.
The guides are given their own authority to do things to their Esper in an emergency, even intercourse is allowed if the condition threatens the Esper if ordinary guiding does not work. This policy was officially issued by the government because if there is corruption of Esper or, in other words, self-detonation due to the uncontrollable power inside his body, an entire region could be destroyed. The safety of the citizens was far more important.
