Andy, using some of the money inherited to him by his father, traveled to Japan, in order to train himself in what he had learned to be the most deadly martial art in close-combat: Kopo-ken. He then went to see the great Hanzo Shiranui, a very skilled ninja who also happened to be a Kopo-ken master. Andy pledged for Hanzo to train him, and Hanzo, seeing the dedication and spirit in his eyes, accepted his offer.

Andy began to train in the mountains of Japan, amidst the forests and rivers. He first only thought of Geese, and he was unlucky in learning the basics due to his stubborness. With the help of constant training and the advices of his master, Hanzo Shiranui, Andy managed to mildy surpress his feeling of revenge. Now completly dedicated to his skills, Andy began to make exceptional progress, and quickly began to learn the more advanced skills of Kopo-ken.

During his stance in Japan, Andy met the beautiful grandaughter of Hanzo, Mai Shiranui. While he managed to completly ignore her for the first couple of months, Andy began to involve himself more and more with the young red-haired girl. Although he has developed strong feelings for her, Andy always pretends to be uninterested, since he thinks of Mai as a foster sister, due to his admiration towards Hanzo as sort of a paternal figure.

After the completion of his training period, Andy decided it was time to go back to Southtown to reunite with his brother, Terry (despite the evident sadness of Mai). During his trip back, he saw a fight between two Muay Thai fighters in a secluded area of Japan. Seeing the very impressive skills and arrogance of one of the Muay Thai fighters, Andy decided to challenge him. Of course, it wasn't an official bout, but the Muay Thai fighter accepted anyway. However, his happiness soon ran away as Andy began to show his incredible skill, and finally, defeated the astounished Muay Thai champion. However, the Muay Thai warrior just laughed, and shaked Andy's hand. He introduced himself as Joe Higashi, world Muay Thai champion! Ever since, both have become the best of friends, although ever since that moment, Andy thinks Joe always talks too much...

Andy and Joe agreed to go back together to the United States, and reunite with Andy's brother, Terry, in order to exact revenge on Geese. Andy then was informed by Terry upon his return that there was going to be a tournament called "The King of Fighters", and that the winner of the competition would end up fighting Geese. Andy's sense of revenge once again grew strong, truly straying him from the true sense of fight. Although he managed to gain enough road in the tournament, he couldn't win against the mighty Geese, due to his rashness and too much emotion. His brother was the one who, in the end, who managed to defeat Geese. Seeing that revenge blinded him, Andy then began a new journey ever since: to surpass his brother's skills, and perhaps defeat him in battle.

Once in a while, Andy travels back to Japan, where he resumes his training and continues to improve his skill. Of course, he is constantly pestered by Mai, and although she has grown into quite a woman during the last few years, Andy still tries to remain focused on his skill improving, and this requires quite some willpower, because no normal man would ever resist Mai's attributes!

Andy has always agreed to follow his brother Terry whenever he decided to enter the new version of the King of Fighters tournament, not as much as helping him, but just to show who's the best brother around! He was about to not enter in the King of Fighters '97, despite Joe's pestering, but since his brother decided to enter as well (to investigate on Geese's involvement in the tournament), he had no choice but accept as well.

All seemed to be perfectly normal when Terry received the invitation to the King of Fighters '99 tournament, since he and Joe would be joining once again, and he would be glad to show his brother what he had learned the last two years! However, it seemed they needed a fourth team member. Before Andy could think about anything, a person requested the fourth position in no time. Andy was more than surprised that it had been Mai, who didn't lose anytime in taking advantage of the situation to be close to Andy! Before Andy could object anything, the tournament was well underway....

The battles of the Lonely Wolves finally took them to a sewer, where they had been scheduled for their next battle. Suddenly, the sewer began to tremble, and began to crumble! Andy dashed right out, but Terry remained for some unknown reason...Andy tried to save his brother, but the rocks had already falled and blocked the pass. Andy wonders about the fate of his brother, but deep within, he knows he just can only train harder for the next time they meet!

Andy's training would once again be put at test in the year 2000, to prove his worth against the menace of NESTS. This time around, Mai had left the Lonely Wolves to join her old friend Yuri Sakazaki. This eased Andy's mind, but not his soul. He felt a bit guilty for having mistrusted Mai in last year's tournament, but there was no time to be sorry. Andy should not fail his brother Terry's trust this year, and so, Andy focuses all his inner strength into finishing the evil reign of NESTS!

Ironically, the final battle takes the Lonely Wolves to Southtown: Andy's city of origin. Andy feels bad about how Southtown keeps degrading itself by the actions of the crime lords, but he also feels somewhat assured for being at home again. But since NESTS was around, there was no kicking back. Andy and his friends are directed to the factory zone of Southtown, where NESTS is suspected to be hiding out. Andy and Terry know this well, and lead Joe and Mary there. By the time they reach the factor district, a legion of soldiers are found surrounding an abandoned factory. Andy wonders that this is odd, but as soon as they approach the soldiers, they begin to fire! Fighting for their lives, the Lonely Wolves have to deal with an army of NESTS agents! Andy helps out in order to knock the corrupt troops down.

While fighting inside the factory, the troops keep falling like chess pieces. But more seem to appear everytime they fall. Andy begins to feel somewhat tired, but has decided to keep on fighting, not allowing his friends and brother to die. Suddenly, the whole building begins to shake, and the soldiers freak out instantly. Terry feels something wrong, and with right reasons: a wounded soldier reports that the Zero Cannon has just been fired, and that the city is doomed! During the previous shock, the building begins to fall down at the seams, and Terry is knocked by a falling rock. Andy is shocked and stops at nothing to help his brother, but Terry pushes him aside, and urges him to escape. Andy looks at Terry's eyes, and recognizes his brother's determined look. Andy nods, and leads the others to shelter.

Minutes later, all is gone. Southtown had crumbled down to nothing. Andy feels a great deal of pain in his heart, for the city that he has been raised in has fallen, but he knew it was just a matter of time, as Southtown had always lived upon the principles of fighting, and it could only lead to destuction. Suprisingly, Andy knows Terry is alive, because he knew, by his brother's sight, that he would be determined to come back soon, as stronger as ever. Andy gives a slient promise that he, too, will keep on fighting, and training to become ever stronger and not lag behind his legenadary brother. In the meantime, he still has to cope with one little problem: having to avoid Mai's crazy marriage attempts for one whole year!

As the year 2001 looms over the horizon, Andy decides to take a trip back to Southtown, however, he tries his best to avoid Mai at any costs (he has left his student, Hokutomaru, to deal with her in the meantime). There, in the middle of the devastation that rules the city, he finds his brother Terry safe and sound, lending a helping hand to the orphans in Southtown, who had lost their parents in the Southtown explosion. Andy watches with joy how Terry overcomes his sadness, and claims that he will fight to give the orphans a new home! Andy notices a little kid by Terry's side. His blond hair makes him look like Terry's disciple, but his inner energy...what was it? Andy can't think about that anymore, since the next King of Fighters tournament quickly arrives!

Andy employs his maximum strength against his opponents, as he gets more and more recognized in his own right. His efforts find a deserved reward: the destruction of NESTS. However, even after their downfall, Andy still has to make amends and settle down the raging fury of Mai!

As explained before, being a sentimental fellow, Andy has very extreme cases of depression, like when fighting in order to exact revenge. Since the only thought on his mind was hatred, he was distracted from battle. However, Andy, when not disturbed, is always a cool and serene guy, a good natured fellow at heart. He also seems to be very serious around the always-kidding Joe! Ever since his sttuborness to defeat Geese, Andy has decided to hide his emotions, even his love for Mai, but from time to time, he shows how much she cares for her, but he doesn't want to make it too evident!