Goku and Krillin want Master Roshi to train them, but he sets them a test first: bring back the sleeping princess from a distant castle. They set off toward the castle, with Bulma and the others following. The trial takes them into a place inhabited by monsters rather than an ordinary royal household.
The journey gives Goku and Krillin a shared goal before their training begins. Inside the castle, Bulma falls into Lucifer’s hands, giving their errand a more immediate danger. This is the 1987 animated film, separate from both the original television series and the first Dragon Ball movie.
Goku and Krillin see the castle as a way into Roshi’s training; Bulma and the others follow them during the summer holidays. Lucifer, meanwhile, has plans that have nothing to do with the boys becoming pupils. Bringing those different motives into one place gives the adventure more than a task to complete: the friends following the boys are entering the same danger.
