Wansū is considered a Tomari-te kata. One classification of traditional Okinawan karate systems distinguished them by the village where they were practiced: Shuri, Naha, or Tomari. Kyan learned it from Maeda Pechin 真栄田 親雲上, a friend or student of Matsumora Kōsaku. "Pechin" is not a name, but a title designating a mid-level member of the scholar-bureaucrat class of the Ryūkyū Kingdom.
Key points from Shimabukuro Hanshi:
Ikkyodō 一挙動, simultaneous receiving and attacking.
Pushing an attacker to create distance for thrusting, striking, or kicking.
Simultaneous punching and kicking: occupy the opponent with the hand while attacking with the foot.
Throwing: kataguruma 肩車, "shoulder wheel" throw.
Close cross-body side punch.
Adapted from the Seibukan book by Shimabukuro and Smith