Little is known about Bantu's background outside his history with Tiki and his strong resistance to madness, unlike other Manaketes. He is an elderly Manakete who took pity on the Divine DragonTiki, who is forced to constantly sleep otherwise she would go insane. He decided to free her and travel with her, keeping her sanity intact. He was separated with her, and joins up with Marth to save her.
In the second book, he is once again separated with Tiki by Gotoh's orders and he eventually meets up with Marth to help him again in the eastern village on an island by Cashmere bridge, when theft stole his dragonstone. In his ending he abandons his Firestone and leaves for parts unknown.
In FE1/11, You can find him in a village to the south inside some walls during the chapter Lefcandith Gauntlet. He starts out with no weapons and looks for his Firestone, which can be obtained by visiting a village during Champions of Aurelis.
He can be a decent Manakete to use in battle, but has bad growth rates and is statwise considered of lesser use when compared to Tiki or Nagi. Bantu rejoins the army in Book 2 of Mystery of the Emblem, and has statiscally not changed much. For reasons unknown, Bantu is not able to use the Ice, Wyvern, and Magestone at all in the original Mystery of the Emblem. This has changed in the remake where Bantu can use those dragonstones.
In the later stages of the game, Bantu's growth makes him fairly weak compared to most of the other characters, but he is required to recruit Tiki at a later stage in Fire Emblem: Shadow Dragon.
An advantage to Bantu in the original Ankoku Ryū to Hikari no Tsurugi is that his Firestone has infinite uses allowing him to be used as an effective tank against enemy units.