They're both under-aged, and isn't the age of consent in Japan 13 years old? People need to do a little research. Despite what this chapter implies, Keita actually has an amazing level of self-control; in fact, I'm not sure I've ever seen a teenage boy with such ability to resist his natural urges. I keep wondering if the author ever did any dating during his teenage years. In this case however, I'm fully expecting the next chapter to bring someone or something to interrupt what would typically be a perfectly normal response by a boy his age who is attracted to girls.