Saiki/Story

The King of Fighters XIII
Saiki is the leader of Those from the Past, serving as the mysterious aforementioned "master" of said group from the "Tales of Ash" story arc's earlier installments. A being that has been described as the Western emissary of Gaia, he desires to gather life energy throughout the tournament to reawake Gaia's will and use the entity for his own means. To do so, he requires a particular ceremony to open a direct doorway to it. In the tournament finals, he appears to the winners to kill them, in order to gain the energy required to open the gate. When Mukai volunteers to deal with the winning team, Saiki isn't up to seeing his follower fail yet again and absorbs Mukai's energy into himself. With their combined strengths, Saiki faces the fighters, hoping to sacrifice them.

After the fight, Saiki remarks that they are doing well, though not good enough to satisfy him. He then suddenly notices that, instead of opening, the Gate was closing. Before he can suspect his followers of betraying him in some manner, Ash uses this moment of weakness to rob Saiki of his spirit. But, contrary to Ash's plan, Saiki finds him to be a suitable new host, manipulating the youth's body as his own and desiring to complete the job by fighting the winning team once again. He is defeated, however, and as Ash manages to retake control over his body after the battle, Saiki orders him to cross the gate so they can retry again. Ash refuses to restart time with Saiki, resulting in both being erased from existence.

The King of Fighters XIV
Verse's defeat during the events of The King of Fighters XIV had released numerous souls and has caused many who have perished throughout the series to be brought back to life. Because Ash was revived regardless of his existence being a paradox, it is currently unknown if Saiki was revived with him.