Ninja Gaiden I
Foster assumes a minor role in the first game. A young ninja named Ryu Hayabusa travels to America as part of his father's request. While Ryu is in America, he is kidnapped by a mysterious woman. Later, Ryu is awakened by the same person who abducted him. She gives him a mysterious, demonic statue and leaves without revealing any more information. Confused, he takes the statue and leaves as well. Soon, Ryu finds an archaeologist named Walter Smith who was an acquaintance of Ryu's father, Jô. Ryu shows his statue to Walter who has a similar one. He enlightens Ryu about them. Together, the statues are capable of resurrecting a powerful demon that died 700 years ago. During the conversation, a masked figure suddenly breaks into the cabin and steals Ryu's demon statue. Ryu chases him and manages to retrieve his stolen statue. When he returns to the cabin, he finds Walter mortally wounded and his own statue stolen. A moment later, Ryu is captured by three armed men.
Ryu is then taken to the CIA where he meets Foster, the head of the agency's auxiliary unit. Foster tells Ryu that he was abducted by Irene Lew who is one of the CIA's agents. He explains to Ryu that they have been monitoring the activity of someone named Jaquio. Jaquio wishes to gain the demon statues in order to summon the demon. Foster orders Ryu to eliminate Jaquio. Ryu parachutes into the jungle of Brazil. He journeys through the jungle and ascends the mountains towards Jacquio's temple. When Ryu arrives at the temple's throne room, he confronts Jaquio. Irene is also being held captive in the same room. Jacquio threatens to kill her if Ryu doesn't hand over the demon statues. He reluctantly gives the demon statues in exchange for Irene's life but he is tricked. Ryu falls through a trap door but he manages to return to the throne room. He then engages Jaquio in a battle. Ryu manages to kill Jacquio but the demon is summoned during a solar eclipse. Ryu is able to defeat the demon before the temple collapses. He and Irene escape to a nearby cliff. Irene then receives a call from Foster on her radio. Foster instructs her to kill Ryu and take the demon statues. She refuses and throws the demon statues into a tree. Ryu overhears the conversation and he vows revenge against Foster.
Ninja Gaiden III: The Ancient Ship of Doom
Foster assumes a major role in the third game. Directly after the events of Ninja Gaiden I, Foster hires a man named Clancy. Together, they build a laboratory near the temple ruins and experiment on inter-dimensional life forms. Irene Lew, Foster's ex-agent who was originally instructed to kill Ryu Hayabusa, spies on the place. Foster sends a clone of Ryu Hayabusa of to kill her and frame the real Ryu. When he finds out, he investigates the laboratory. Ryu encounters Clancy who instructs Ryu to visit a place called the Castle-Rock Fortress. Confused, Ryu stills follows the instruction.
Along the way, Ryu encounters a live video feed of Foster in a cave. Foster denies killing Irene Lew. He claims to be waiting at the Castle-Rock Fortress. Soon. Ryu reaches the Castle-Rock Fortress. Foster and Ryu encounter each other deep inside the fortress. Ryu's clone appears a moment later. Before Foster can say or do anything else, he is confronted by Irene Lew who managed to survive. She attempts to attack Ryu's clone but it transforms. Ryu kills his own clone, but then the castle shakes. Clancy double crosses Foster when reveals the Castle-Rock Fortress is actually an inter-dimensional warship. Clancy then escapes through a portal. Foster attempts to follow Clancy but his body is ripped to shreds.