Yahiko - with Kaoru

Training is limited by a terrible teacher.

Early on in the series,  Kenshin and Kaoru ran into a boy who was being forced into pickpocketing from their town.  After leaving his tormentors,  Yahiko joined Kaoru's training school,  becoming her one and only student.  However,  since then Kaoru has been nothing of use to this hard working child.  View the picture above.  Throughout the series,  Kaoru only taught Yahiko one move.  That's it,  ONE move!!  Hold the stick above the head,  and swing foward.  That is the ONLY move Yahiko knows how to teach.  Yahiko is obviously grateful for being allowed to sleep at Kaoru's dojo,  but doesn't seem to like her at all.  He "jokes" by calling her ugly,  but deep down he probably means much of what he says.  After all,  anyone would be frustrated after being taught only one move!  And even after such terrible teaching,  Yahiko somehow STILL manages to learn new moves and strategies during combat!  And when he is in combat,  he is PROTECTING KAORU in many occaisions!  This is pitiful.  How can the student protect the teacher?  Obviously Yahiko learned many of his moves by watching Kenshin,  and applied them to his arsenal.  But with Kaoru as his main trainer,  he may never excel.