What is Aiki-jujutsu

Trying to describe it with words is challenging because it contains concepts that are unfamiliar to Westerners. We chose to name our style “Aiki-jujutsu” to distinguish it from Brazilian Jujutsu and MMA systems.
The “Aiki” of Aiki-jujutsu can be thought of as redirecting force softly rather than clashing with it. An example would be if a stick was swung at your head, you move inward to avoid the momentum of the fast-moving part and rotate your body to follow the opponent’s swing. The idea is to off-balance the opponent with their own movement and follow up with a throw or joint lock. Ideally the movement is in a very relaxed way with a calm mind.
This is in contrast to a style like Karate or Taekwondo that may choose to use the forearms to block the stick and then follow with punches and kicks.

Here is a good description of Aiki from Wikipedia