After returning to West City on a weekend, John visited Bulma's home.
Bulma's mother welcomed John warmly, teasing him as usual.
John asked, "Auntie, are Bulma and Dr. Briefs home?"
"Oh, they are at home. Bulma should be in her room watching TV, and your uncle is probably in the lab," Bulma's mother replied. "You know the way, right? Do you need me to find a robot butler to guide you?"
John thanked her and said, "No thanks, Auntie. I can find my way; I know the layout of your house well."
Arriving at Bulma's door, John knocked.
"Come in!" Bulma's slightly annoyed voice came from inside.
"Bulma, what's wrong? You look upset. Where's Yamcha?" John pushed the door open and entered.
Bulma replied, "Hmph! Him?! He hasn't thought about his girlfriend at all since he got back; he's been holed up in the dojo practicing with others, trying to surpass you in the next martial arts tournament."
At this point, the relationship between Bulma and Yamcha had already developed cracks. Bulma desired a gentle and understanding prince charming by her side. However, Yamcha now resembled a wild wolf filled with martial spirit that she couldn't tame. He was driven by his ambition to improve his martial arts skills.
Eventually, he realized that no matter how hard he tried, he couldn't keep up with Goku and the others—not due to lack of effort but because of his inherent limitations. This realization led him to abandon his martial pursuits.
Feeling ashamed to face Bulma, he began wandering around West City, getting involved in baseball instead, which ultimately led to their breakup.
John had never been optimistic about their relationship from the start but didn't want to interfere since matters of the heart needed clarity from both parties.
After complaining for a while, Bulma asked John: "By the way, what did you want to talk to me about?"
John replied: "I need your help with two things."
"Two things? Let's hear them! If I'm not interested in what you say, I won't help," Bulma said knowingly that John's requests would likely involve creating some special machine.
John explained: "One of them is something you can easily handle; the other might require a bit of thought from you."
Hearing this piqued Bulma's interest as she asked: "Tell me! If it sounds fun, I'll help you."
John continued: "The first thing is that I need a Dragon Ball Radar."
"Dragon Ball Radar? What? You want to make a wish from Shenron?" Bulma asked curiously.
John clarified: "Not exactly; I have other uses for it. But please let me keep some mystery—just prepare it for me."
"Alright then! What's the second thing you need my help with?" Bulma replied nonchalantly since Dragon Ball Radars were standard products that didn't require much effort on her part—she could just use the computer at home to automate its production.
John went on: "The second thing is that I want you to help me build a gravity adjustment room."
"A gravity adjustment room?!" Bulma asked in confusion. "You mean a machine that alters local gravitational forces?"
"Yes! The gravity on Earth feels a bit light for me; I want you to create a machine that can increase the surrounding gravity so I can continue training my body in a high-gravity environment," John explained.
"That's actually a great idea! If I can build a gravity room, Yamcha wouldn't have to go outside to train anymore; he could just train at home in this gravity room," Bulma said excitedly.
Although John wanted to interrupt her fantasy and tell her that the issues between her and Yamcha were not solely about martial arts training, he held back his words.
"Alright! No problem! I'll take on this task. When do you need it?" Bulma asked.
John replied: "There's no rush; just give me the Dragon Ball Radar first. As for the gravity room, I might need it in four or five months."
About a week later, a brand new Dragon Ball Radar appeared in John's hands.
He didn't go out searching for Dragon Balls yet since they wouldn't appear for another month; instead, he chose to recuperate his body in West City for now and prepare himself physically for new training journeys ahead.
(Everyone knows why John needs the Dragon Ball Radar now, right?)
Days passed by without any training as John focused on balancing his body and energy while meditating on his spiritual cultivation atop nearby mountains outside West City.
Finally, on the 366th day since his last wish with Shenron, John's Dragon Ball Radar detected seven Dragon Balls' locations.
"The Dragon Balls have finally transformed from stones into actual Dragon Balls! It's time for me to set off; my new training journey begins now!" John had long prepared for this upcoming training plan.
First, after more than a month apart, he returned to Bulma's house again asking her for an airplane capsule along with a small submarine capsule and several large storage capsules.
(Now everyone knows what John is planning to do!)
Although it was strange why John needed so many large storage capsules, Bulma was too preoccupied with difficulties concerning the gravity adjustment room to delve deeper into John's intentions.
Once everything was ready, John bid farewell to Bulma's family and flew off toward Master Roshi's place in his airplane.
It didn't take long before he arrived at Kame House where Krillin was doing push-ups under Master Roshi's supervision—1,000 every day.
As John landed the plane slowly and stepped out, Master Roshi curiously asked: "John! Aren't you off adventuring? Why are you here today?"
After respectfully bowing to Master Roshi he said: "Master Roshi! I came today hoping you could tell me where Korin Tower is located?"
"Korin Tower?!" Hearing John's inquiry about Korin Tower surprised Master Roshi because Korin Tower was an even more mysterious existence than the Dragon Balls; most people actually didn't know its location.