L. A. Boom Boom (Ｌ.Ａ. ブンブーン Eru Ē Bun Būn) is a minor antagonist featured in Steel Ball Run.
L.A. is the youngest member of the Boom Boom Family along with his father Benjamin and his older brother Andre. Participating in the Steel Ball Run, he attacks Johnny Joestar and Gyro Zeppeli to eliminate competitors.
L. A. seems to be a nearly twenty years old boy, with long hair, but no particular physical character.
His personality is really interesting indeed: he doesn't seem to be perfectly sane, probably because of the loss of his mother and the strong presences of the other two members of the family. He is shown crying in numerous instances, and generally acts like a child, calling his father 'daddy' and is constantly in need of his help due to his lack of confidence. His humor changes from happy to sad, from scared to angry very quickly.
Compared to the other members of his family, he seems to be of lower intelligence, but has sudden moments of keen observation which are only met with his family's scorn. For this, Benjamin calls him 'the family's smartass'.
After his brother Andre tricks Gyro and Johnny and manages to transform the first into a human magnet, Benjamin and L. A. attack them unsuccessfully. However, Benjamin quickly elaborate a new strategy, turning Johnny and Mountain Tim into magnets too.
His plan seems to work, but Gyro manages to warn Mountain Tim of the incoming danger: the sheriff manages to regain control of the situation by exploiting the power of his Stand. It is at this point that L. A. gets in action, using his Stand to immobilize Gyro and Johnny and cutting Oh! Lonesome Me, forcing the three to collide and almost killing them.
In fact, Johnny manages to react with his new power, killing Benjamin and neutralizing the magnet field. L. A. attempts to avenge his father, but he loses a foot because of Johnny. With his father lying in his arms, L. A. reveals that their actual goal was killing Gyro in order to earn his bounty. Even if all members of the Boom Boom family are doomed, L. A. says that Gyro won't see the end of the race, because other people will try to be rid of him.
After their father's death, it is unknown what happened to him and his brother.
- Main article: Tomb of the Boom 3
The Boom Boom family's Stand, Tomb of the Boom, grants every member with the ability to manipulate iron, though every member develops this ability in a different way. In L. A.'s case, it allows him to manipulate iron sand and to use to immobilize his victims. He seems to be able to attract iron items at short distances and, since human blood contains iron, he is capable of killing a person by extracting his blood. L. A.'s Stand manifestation also seems to be the most combat-oriented of the family.