Seiyunchin is a very old Chinese kata, and it's origins are probably in the Hsing-I internal system. All of the movements are hand techniques with no kicks, a very unusual feature. It is in the tiger series of katas.
The following thoughts on the kanji for this kata are from Chuck TC Kwan (email@example.com):
1st kanji translates as system/method and the 3rd kanji battle/fight/war.
I read the kanji as "pulling" in the sense of "sucking/drawing/leading/setting up the person into a trap", (eg: an "attack by drawing") in JKDC terminology.
Thus, I read and speculate Seiyunchin as a kata which illiustrates a system of drawing the opponent to make the initial attack into your counter or traps. I see Seiyunchin as a more generalized kata showing different methods of engaging the opponent in a favourable manner (the idea of the 2nd kanji).
It begins by moving the right foot forward into a 45 degree Shiko Dachi and performing Morote Sukui Uke with Muchimi. Then, place the hands back to back as they are raised to the chin, keeping the elbows close to the chest and pointing the fingers upward. Next, execute Morote Gedan Barai, then open both hands right Sukui Uke pulling the left hand to the side, then perform a right Chudan Hiki Tsuki and a left Hira Nukite Tzuki.
You then step forward with the left foot into a 45 degree Shiko Dachi and repeat the sequence using the opposite hands, followed by stepping forward with the right foot and repeating the opening sequence once again.
Next, form a fist with the right hand and turn it palm up on top of the left hand and step back with the right foot into Suri Ashi, then continue to slide the right foot forward into right Heiko Dachi while simultaneously turning the hands over and performing Hoju Oshi. The right foot is then pulled back into left Han Zenkutsu Dachi while pulling the right fist into chamber, leaving the left hand where it was, then deliver a right Hiji Ate into the left palm.
Slide the right foot forward into right Renoji Dachi while performing a right Hojo Uke, then step forward with the left foot into a 45 degree Shiko Dachi and execute a left Gedan Barai, followed by stepping back in the same line into Shiko Dachi facing the opposite way and executing a right Gedan Barai. Next, slide the left foot into left Renoji Dachi and perform the Hojo Uke, followed by the double Shiko Dachi-Gedan Barai movements.
Next, step back with the left foot into right Shiko Dachi in line with Shomen facing to the front and perform Hari Uke with open hands, then step back with the right foot and repeat the technique facing in the opposite direction. Then, sweep the right foot forward into right Heiko Dachi and deliver a right Jodan Uchi Uke into the left palm, immediately followed by sliding the feet forward into the same stance and delivering a right Jodan Uraken Uchi, again with the elbow resting in the left hand.
Slide the right foot across the front into Bensoku Dachi and pivot 135 degrees to the left into left Heiko Dachi while performing a left Chudan Yoko Uke and a right Gedan Barai. Then, step forward with the right leg into Shiko Dachi at a 45 degree angle and execute a right Age Tsuki while dropping the left hand to the solar plexis and follow with a right Jodan Uraken Uchi and then a right Gedan Barai. Step back with the right foot on the same line into Shiko Dachi and perform a left hand Gedan Barai, chambering the right hand.
Turning to face Shomen, draw the right foot back into right Neko Ashi Dachi, folding the arms across the chest and deliver a right Hiji Age and a left Ushiro Hiji Ate, then step back into left Neko Ashi Dachi and repeat the same hand movements. Next, step over with the left foot into Bensoku Dachi and turn 135 degrees to the right, repeating the same sequence upto the second Neko Ashi Dachi-Hiji Age-Ushiro Hiji Ate combination using opposite sides.
From right Neko Ashi Dachi, slide the right foot forward and take a large step into right Heiko Dachi while executing a left Shotei Otoshi Uke together with a right Jodan Uraken Uchi, then take a large step back into left Neko Ashi Dachi while simultaneously raising both hands over the head and bringing them together back to back. Slowly lower them with tension, separating the elbows into Kuri Uke. Yame.