Memory lose and age regression. Title refers to the psychological test of associative memories regarding baker as a profession versus Baker as a name. Thus, the title manifests that associative memory in Hideyuki's memory loss and age regression where his memory loss was from his trauma of being seen and found out. Also that he regained them because he saw someone which is associated to the trigger that caused his trauma. This is incestuous, but the execution solidifies its theme without encouraging nor romanticizing incest. It's a story of two brothers and the people who, although they try to intervene, understood the "depth" of their relationship (not necessarily the details of what their relationship entail).
Baker Baker Paradox