She could confess. Or even if she didn't directly and unambiguously confess immediately, she could be a whole lot more direct about it. I don't know if Akihito really was a child soldier in Afghanistan and Sudan, but he clearly has got his own issues weighing down on him, plus he absolutely needs to stay on top of his studies, all the time. Now he feels somewhat responsible for Charlotte and Emma, having gotten involved with them. Feeling responsible for them will prevent him from so easily seeing romantic undertones, to some degree. He's not the kind of guy who would be helping them just in order to get something in return.