He foresaw that Hao Asakura was inside the womb of his daughter Keiko when she was pregnant, so he planned to kill the child as soon as it was born. When they discovered she was carrying twins, Yohmei reluctantly decided he would rather kill both of them than risk allowing Hao to be reborn. However, Yohmei hesitated for a moment as he was hit with remorse for killing his own grandchildren, and that moment was all that Hao needed to summon Spirit of Fire and protect himself.
When Yoh was young, he was brought up and trained by Yohmei, who had a very hard time doing it due to Yoh's laziness and stubbornness.
Yohmei was the one who suggested that Yoh would go inside the Tunnel of Tartarus (Yomi's Hole in the Japanese anime and manga) in order to improve his furyoku (mana). Anna's teacher is Yohmei's wife, Kino. Kino and Anna are similar in temperament, so Yohmei is often hit hard on the head by Kino and he fears getting on Kino's bad side, much like Yoh is of Anna.
Onmyōjutsu (Yin and Yang Technique) - using his knowledge in onmyoudou, he is somewhat able to see the future.
Shikigami- he can create and control any number of these small OverSouls using small leaves as mediums. Yohmei almost constantly uses these, even outside of combat, to do small tasks like fetching items, holding the newspaper, and so forth. Strangely, these spirits can move through telephone lines.
AsakuraShikiOnmyōJutsu HyakuShikigami (Asakura Style Yin and Yang Technique - Hundred Shikigami) - Yohmei's favoured technique which creates countless Shikigami, he can surround an opponent and attack them from all directions at once.