Was for After Benimaru told his story to Wolf, he then decided to explore the room he was in, where he saw plans, initial drawings for submarine concepts. Which piqued Benimaru's curiosity, looking at the books in the collection of Wolf, trying to learn more about the technological advancement here, as he was a Mechanical Engineer, specializing in transportation. While he still has his memories, the Essence of Self enhanced his brain, making him absorb information faster and with instant recall, which made Benimaru read the books at a fast rate.
Meanwhile, Wolf, while working, saw that Benimaru was picking up books that he had used before to teach himself the basics in mechanics. When Wolf saw that Benimaru was just flipping through the pages as if he wasn't not reading it, he just continued his work, not knowing that Benimaru was becoming master of the craft a lot more, Benimaru then got to the notes of Wolf, where he absorbed the experiences of Wolf in every inventions he made, as all of it was listed in multiple journals.
After a few hours, Benimaru finished, his head running calculations on how to improve the inventions of Wolf. He then looked at the counter, where he found a failed version of the grenade. In the notes, it was supposed to produce an explosion equal to an explosion of a missile in his past world, something that Benimaru did not know how is it possible, but he did not really care, he just combined the logic here in One Piece with what he know, reassembling the grenade into a functional one, which shocked Wolf.
"How did you know to do that?" Wolf asked Benimaru, curious about it since Benimaru just disassembled his entire invention without it exploding, as even he can't do it easily and as fast as Benimaru, not only that, he also reassembled it.
"Well, I was reading your books and notes, that's how I learned how to do that," Benimaru said, answering Wolf's question as if it were just nothing.
"You mean when you flipped the pages of the books, you call that reading?" Wolf said, not fully believing Benimaru,
"Yes, I can remember anything that I read. I seem to have that even before, but nothing in our hometown piqued my interest until now," Benimaru said, creating another lie, as he did not want to overcomplicate things in the future.
"Alright, let's test your grenade then, as to see if your modification works," Wolf said, challenging Benimaru to test his product.
"It's not really my grenade as you created it, i just improved it but whatever you feel like," Benimaru said, confident in his abilities.
Wolf and Benimaru then went outside, and walked towards the jungle further as Wolf did not want to damage his house, while Benimaru just followed behind him, after 10 minutes of walking, they arrived at their destination, it was a waterfalls in the jungle, where it was so remote that no one was living in it.
Wolf then proceeded to unpin the grenade and toss it in the water, which is 100 feet deep. After 5 seconds, it released a big explosion, which splashed a lot of water upwards, and a lot of creatures living in the waterfalls, mostly crocodiles, were found dead, when the aftermath of the explosion cleared, Wolf and Benimaru were seen, as Benimaru have a calm expression while Wolf have an exaggerated shocked face, complete with everything as his mouth was opened so wildly that Benimaru thought that the physics in One Piece world were not working properly.
"See, it works now, it seems you are a great inventor, with only a few tweaks missing in your experiments," Benimaru said, complimenting Wolf, who was just touched by the words of compliment, as no one called Wolf a great inventor except for himself.
After testing the grenade, Wolf and Benimaru go back to the house, where Wolf asks Benimaru to help him modify the submarine he was planning to build, any design flaws or any improvements, which Benimaru gladly helps with. The time passed as both Wolf and Benimaru were focused on their work, so they did not notice that 4 teens entered their home it was Law, Bepo, Shachi, and Penguin, back from their work.
"Hmmm, where is Wolf-san? He would always greet us in the entrance," Penguin commented, as he was used to seeing the old man greet them.
"Wait? You don't think the passed-out kid we helped kill Wolf-san, don't you?" Shachi said, jokingly, making the 4 laugh, until they realized that it could be a possibility, the 4 panicked and goes to the lab where Wolf was normally working on his projects. What they found in there shocked them to the core and horrified them.
In the room, they could only see the lower half of Wolf, where he was lying on the ground, with Benimaru holding up a hammer, as if he just hit Wolf, making him pass out. Law, who owned his life to Wolf and treated Wolf as a new friend, immediately felt anger as the memories of the death of Rosinante were still fresh, immediately activating his Devil Fruit. While Benimaru, were just attracted by the noise that the door made when it slammed.
"ROOM," Law said, where a sphere was seen expanding into the whole room, where he swapped the hammer in Benimaru's hand into Bepo, who also got ready to fight. When Bepo got teleported, he immediately grabbed the arm of Benimaru, as if it would prevent him from moving, while the other three attacked Benimaru.
Benimaru, who recognized every one of them, not wanting to hurt them, just punched them all in their heads, making them pass out in one stroke. The commotion created a lot of noise, which attracted Wolf, who was not passed out, but just lying on the ground, inspecting a metal that they were planning to use for the coating of the submarine that Benimaru and Wolf were planning to build.
When Wolf stood up, he saw the 4 passed out, where Benimaru was just looking at Wolf with an expression that say 'he did not start it,' this made Wolf sighed as he ordered Benimaru to lift Bepo and Law, while he would carry Shachi and Penguin to put them into their room. While walking, Wolf who was curious on what happened, just asked Benimaru.
"So what happened?" Wolf asked, still confused about the events that happened in only a few seconds.
"I don't even know, the one with the hat just said Room, when suddenly the Polar Bear one suddenly teleported and grabbed my arm, while the other 3 attacked me, I just knocked them out in a single punch after that," Benimaru just explained, this made Wolf became suspicious of Benimaru as his strength did not match someone that passed out when a pirate that he wasn't in the Grandline attacked his parents vessel, Wolf know that Benimaru's story weren't adding up, but he also respected his privacy, and decided not to ask.