17-year-old Masaki Andoh is the last of the main summons to the netherworld of La Gias, by the emperor of Langran. A typical hot-blooded character, he's great in all sports, but not so great in terms of thinking straight. He's also somewhat awkward around the company of women (this is ironic, since he has acquired an unofficial harem in his stay in Langran). Because of his extreme emotional ups and downs, he was chosen as the pilot for the Masō Kishin, Cybuster, which requires high amounts of prana. When he first arrived in Langran, he was given the Wind Masōki, Jaohm, to pilot, and later he is chosen by Cyfis to be the pilot of the Cybuster. He was the last of the four Masō Kishin pilots to be chosen, albeit by Cybuster, arguably the best of the Masō Kishin.

Both his parents died when he was young, leading to a loneliness complex he developed as a child. However, this was dispelled by the people he met in La Gias. Forever indebted to his mentor, Zeoroot Zenozakis, who was like a father to him, he treats his only daughter, Presia, like a sister he never had. He has feelings for Wendy Rasm Iknart, the designer of the Langran Masōki Project, but things are more complicated when Lune Zoldark has thrown her hat into the ring. Becky, another Masōki pilot, always reminds him that polygamy is common in La Gias, which turns off Masaki and gets him all embarrassed.

Since the guardian spirit of the Masō Kishin only accepts a person with a good heart, Masaki was granted freedom in Langran. He can openly disobey the ruler of Langran without receiving penalties. In fact, it's his duty to oppose any ruler of Langran who threatens the peace of La Gias. The name bestowed onto him, Randoll Zan Zenozakis, is actually an ancestor of Zeoroot, hence in Langran theory, making him Zeoroot’s son. Randoll was also the hero who sealed off Shiva Volkruss several years ago.

Masaki has no sense of direction. Without any guide, he can get lost even if he is inside a battleship, and is hesitant to admit it this weakness. Moreover, it explains why he never chases his enemies who flee from battle, even though the Cybuster is capable of moving at extremely high speeds. He carries two familiar cats: Kuro, a black female, and Shiro, a white male, who constantly make fun of Masaki whenever he’s lost, although they are usually helpless to direct him otherwise. They each pilot a "High Familiar", a funnel-type weapon which launches from the Cybuster.

Masaki's hate of Shu Shirakawa stems from the fact that Shu killed Zeoroot, before fleeing to the surface world of Earth, an event that occurs before Super Robot Wars 2 in the Classic Timeline and before the first Original Generation in the OG Saga, and most likely also happened in the Alpha timeline.

(Source: Super Robot Wars Wikia)