I took the 3-dan shinsa yesterday (9 years overdue LOL) and passed. I had to write this for my essay. Writing it was actually incredibly helpful – I have a lot more I want to say on this subject as it relates to my own kendo.
Yuko-Datotsu is defined as the making of a valid strike, one that would be considered an ippon. Indeed, an ippon is scored when the elements of Yuko-Datotsu come together with ki-ken-tai-ichi (which itself shares many aspects with the elements of yuko-datotsu). Yuko-Datotsu is achieved when five elements – Kamaeru, Semeru, Toraeru, Utsu, and Zanshin – are brought together into a cohesive whole in a strike.
The first of these elements is kamaeru. Kamaeru is to assume the proper posture. Proper here does not mean “correct” – there is no distinctly “correct” posture. Instead, it means to assume a chudan kamae which is prepared to both attack and defend. Physically, it is to be upright, whilst holding the shinai in a way that does not expose any targets, and to be ready to attack. Kamaeru extends beyond simply kamae. It implies that this upright and powerful posture be maintained throughout the execution of a waza. An example of kamaeru being important is during shiai, where ippon is usually not awarded if the attacker bends and attacks from a sidewards angle in order to move around a kamae, instead of breaking it through seme.
Semeru is the second element, which means to control the center. By controlling the center, a kendoka applies pressure to the opponent with the objective of breaking their chudan. This is the important “conversation” that good kendokas have before the actual physical completion of waza. This “conversation” is actually a fight to control the center. Through semeru one can gain control of the center, and by dominating the center, one can give the opponent the feeling that they can strike when the opportunity presents itself.
Third is toraeru. Toraeru is to recognize and take advantage of an opportunity. With correct kamae and seme, one can determine when the opponent’s chudan is broken and act upon that opportunity with the striking of a waza. I believe that toraeru is just as difficult as semeru. This is because toraeru shows an understanding and application of both the mental/spiritual and physical elements of kendo. Through good kamae and seme, one can break an opponent’s chudan, but without toraeru, one cannot convert this opportunity into an ippon waza.
Utsu, the fourth element, can also be understood as datotsu, an effective cut. This can be further divided into two sub-elements. The first is datotsu-bu – the correct part of the shinai. The waza is considered valid when the strike is made with the monouchi of the shinai, the top third of the blade between the kensen and nakayui. The second component is datotsu-bui – the correct part of the opponent’s armor. Utsu is the physical component of yuko-datotsu. It is important because without being able to physically manifest a waza, the other elements cannot be utilized to their full potential.
The last component of yuko-datotsu is zanshin. Zanshin literally means “residual/remaining heart”. Physically speaking, it means to return to a fighting kamae after the completion of a waza such that one is able to strike again. But along with this physicality is the mental aspect. After the completion of a waza, one cannot think “ok, breathe in, begin again”. One must be mentally alert and be prepared to attack immediately. There is no distinction between the end of one strike and the beginning of the next – they are one and the same.
In yuko-datotsu, one assumes the correct posture throughout the waza, uses seme to control the center and recognizes the opportunity to strike, strikes the correct part of the opponent with the correct part of the shinai, and is ready to strike again after the completion of the waza. In addition to these elements, one must also use the correct hasuji, as the shinai is representative of a katana, and one would not cut with the broad or flat side of the blade. Ki must also be strong. Indeed, although ki-ken-tai-ichi is often discussed separately, I believe that correct ki-ken-tai-ichi and the elements of yuko-datotsu are inseparable and equally important. With these elements, an ippon can be scored by a kendoka.