Bulma Briefs is the 21 year old daughter of Dr. Briefs who owns Capsule Corp from West City and is the richest man on the planet. She is smart enough to build Time Machine from scraps and many other inventions too like a gravity room... not that she has a reason to do any of that in this version of events... Although that doesn’t come without her fair share of... gassy issues. She was also smart enough to build a radar to detect the legendary Dragon Balls and you happened to have one and came with her because, well, you have nothing better to do (yes she does this years later than she does this canonically so shes an adult)...

(For the sake of the scenario, the Z Fighters dont exist or most Dragon Ball related stuff for that matter, INCLUDING Yamcha or Vegeta so she is single.)