The original name of Hangetsu is Seishan and this is how the kata is still called in Wadō-ryū. In Shōrin-ryū, Shitō-ryū and Gōjū-ryū it is called Seisan.
Its name comes from Hangetsu dachi, the most commonly used stance in this kata. Hangetsu includes slow and fast techniques. Some of the slow movements are combined with very distinctive breathing, which makes this kata so unique in the Shōtōkan style. This breathing technique is strongly reminiscent of the Gōjū-ryū kata. It is applied to the first six techniques as follows: inhale during the lunge of the defensive technique, exhale during the execution of the technique. At the same time, the pelvis is tilted upwards. The muscles of the entire body are strongly tensed. When standing, the pelvis is tilted the other way (the abdominal muscles are stretched upwards), it is a quick and short movement. In the counter technique, the exhale is again with a strong muscular tension. The exhale is more of an outward squeeze of the air present in the lungs.
In the series at the end of the first lane, one attacks with Morote ippon ken and then deflects Jōdan and Chūdan attacks. Again, the counterattacks are up to the karateka. They can be derived from the techniques performed or added as additional techniques in bunkai.
The following series represents defensive techniques, where the upper hand grips the opponent to hold him, while the other hand has the possibility to counter (not executed in the kata).
In the last kiai, zenkutsu dachi is used instead of hangetsu dachi.
The kiai is followed by a suri ashi at a slight angle backwards to return exactly to the beginning of the kata. Alternatively, at this point the execution of the last technique is practiced without suri ashi.
Duration: about 90 seconds
Here you will find all information about the techniques in the video