function Responder(name) {
  this.name = name;
  this.response = function (input) {
    return input + "ってなに？"
  };
}

function Unmo(name) {
  this.name = name;
  this.responder = new Responder('What');
  this.dialogue = function (input) {
    return this.responder.response(input);
  };
  this.responder_name = function () {
    return this.responder.name;
  };
}

var u = new Unmo('proto');
var input = "あれ";

console.log(u.dialogue(input));