Approximately 15 years old when the series begins, Bat is a wandering thief and orphan. He originally resided in a small village run by Toyo, but when the food supply began to run out he left so that the younger orphans could have his share. While wandering he is captured and imprisoned at Lin's village, which is where he meets Kenshiro. Impressed by the strength of Kenshiro, he tags along with him (somewhat by force), believing that this way he will no longer have any trouble finding food. At first, he is depicted as a selfish nuisance, but after a while Bat is shown to be a virtuous person, as evident by his reasons for leaving his home village. Bat is rather cowardly and careless and will often jump to the wrong conclusions, but this masks his kind nature and he is usually willing to help out in a situation when he can. Bat is very good at fixing machines and can also drive, an example being a dune buggy used as transportation throughout the first part of the manga. He looks up to Kenshiro like an older brother, and likewise Kenshiro begins to see him as a younger brother.
After viewing Kenshiro's many death battles, he is able to grow remarkably into an expert martial artist. After the time-skip following Raoh's defeat (the segment which corresponds to the Hokuto no Ken 2 anime series), he is the young leader of a band of resistance fighters known as the Hokuto Army (北斗の軍,, Hokuto no Gun?), fighting against the dictatorship of the Imperial General Jakō. He has also fallen in love with Lin, whom he protects without hesitation. When Lin is kidnapped and taken to the Land of Asura, Bat secretly follows Kenshiro to save her (but does not show up until the end of the arc). After saving Lin, who had had her memory erased so that she falls in love with the first person she sees as result of Kaioh's Shikanhaku point, Bat is prepared to let her see Kenshiro first, but Ken walks off before she can wake up and leaves her with Bat. Before he leaves, he tells Bat "My fate is one of constant battle, you are the only one who can truly make Lin happy".
However, Bat is aware that Lin's feelings for him are not genuine and erases her memory again with his limited Hokuto Shinken knowledge during their wedding. When Kenshiro's memory is erased after a thunderstorm (he assumed that Yuria was the one who erased his memory, so that he can be happy with Lin), Bat poses as him during the fight against the blind Bolge, but is defeated and then tortured by Bolge who believes him to be Kenshiro. Bat is ready to die, so Bolge would think that Kenshiro is dead and no longer search for him. However, Kenshiro and Lin regain their memories and they set off to save Bat. Bolge is killed, but Bat is fatally wounded in the fight. In the very end of the manga, Lin chooses to stay with the (presumed) dead Bat, accepting to reciprocate his feelings out of her free will. When Kenshiro leaves Lin and Mamiya, Bat is then suddenly brought to life. Bat was saved by Kenshiro pressing on his pressure points with the use of Hokuto Shinken.