The first thing Miles did when he entered the chamber was to invite all the girls to a party, this included Bell-mere. Once they were in the party he gives them all the [Extreme Pain Resistance] skill, after that he changed their races to high humans. Now you may be wondering why he invited Bell-mere to the party and changed her race even though she won't be joining them and becoming a pirate. The reason is very simple, it's so that when Miles, Nojiko and Nami become pirates in the future, their enemies like the marines cant use Bell-mere as their weakness.
Once their race change was done and the girls had rested afterwards, Miles gave them each a devil fruit and used [All Curse Breaker] on them so they wouldn't have any side effects.
First, he gave Bell-mere a paramecia type fruit called the Plant-Plant fruit which can accelerate the growth rate of plants and control them to their desire. Since she wasn't coming with them this fruit would help her tangerine farm so she can produce more without help from Nami and Nojiko. Next gave Erza the Space-Space to enhance her space-type magic and give her more storage space for her armours and weapons.
Nami was giving the Wind-Wind fruit to enhance her stealth and agility, this would help her if she is trying to steal something quietly or if she is in a head-on fight. Finally, Nojiko was giving two devil fruits, the Rumble-Rumble fruit and the Glint-Glint fruit. The reason she got two fruits was that Miles was planning to make her specialized guns that can shoot concentrated light-type and lightning-type bullets and can also switch to regular bullets with the press of a button.
Once the girls ate their fruits and Miles finished laughing at their reactions to eating them, they all started training.
----
It has been 2 years since Miles arrived in the One Piece world. He and the girls have been going in and out of the time chamber periodically once a month, meaning they have technically been training for 24 years. When their first day in the chamber was finished, Miles found that his card experiment was successful and that the summoned does not expire if the summon card is outside the chamber. Unfortunately, his cards had now expired, but he was able to milk that loophole for all its worth and get many benefits from it.
One of the best benefits of this was that Roger was able to teach the kids more than just how to use haki. He also taught them about how the grand line works, especially how the weather works. This made Nami ecstatic as she asked him hundreds of questions about how it works and how it would affect navigation. Miles, Erza, and Nojiko, on the other hand, didn't care much about that topic so they mostly focused on other aspects of their training.
Miles did, however, want to know how to read the poneglyphs and was going to ask Roger but ultimately didn't. Miles was sure to ask Robin to join his crew at a later date, but that wasn't the reason he did not ask Roger to teach him. It was because Miles was sure there was some ability in the store that would let him understand other languages. He was correct, and while looking through the skills section of the store he found [Universal Language] and bought it.
During their time learning about the grand line and how to fight, they had also all awakened their devil fruits. Except for Nojiko, the girls all awakened their fruits within 5 years, it took Nojiko 10 years since she had 2 devil fruits. Miles on the other hand wasn't able to awaken his fruit yet. He assumed it was because his fruit was 11 other fruits fused together, so he calculated that it would take him around 45 to 50 years to awaken his fruit. He was fine with this since he still had many other things to do and lots of time before he set sail.
In his time when Miles wasn't learning, he was building and designing gadgets, tools and weapons that would be useful during their time travelling. The most important thing he was making was their ship. Miles was not going to sail in a normal ship that could be obtained by going to your local shipyard and buying one. Miles was going to make a ship that this world has never seen and will never see again.
The ship Miles made was a modern-day frigate made of an Uru-Vibranium-Adamantium alloy, the ship is virtually indestructible and would be able to take any amount of punishment. It had large artillery cannon on the front the ship and smaller artillery on the sides, behind the main cannon, hidden under the deck was a launcher that would fire off guided long range or short range white phosphorus warhead missiles at enemies when needed.
The ship was to be fueled by a medium-sized arc reactor and would be able to sail itself with the help of its built-in A.I Jarvis, or manually by a person at the helm.
Finally, the interior of the ship looked more like a cruise ship then battleship and it had enough single rooms for 30 crew members, each room had its own bathroom with shower and a jacuzzi bathtub. The kitchen was a top-tier kitchen that looked was ripped right from the pages of shokugeki no soma.
When Miles was finished building the ship, it was painted black with gold accents. At the back of the ship in bold golden font read the name Death Rider.
----
Back to the present, Miles was currently sitting under a tree near the orange grove thinking about the near future.
'Arlong and his crew should be arriving at the island soon and Kuina's death will be this year as well, *sigh* I wish I knew the exact date when these things happen.'
{I can tell you that Arlong should be arriving tomorrow, but I don't know when Kuina dies so you should probably go to Shimotsuki Village as soon as possible.} She said nonchalantly.
'...Why do you know when Arlong will arrive but don't know when Kuina will die?'
{I did a scan of Conami Islands and Arlong's ship is stopped just off the coast of the archipelago. Kuina's death, as you said, never had the exact date specified in the manga/anime, so even I don't know when it happens.}
When Miles heard her explanation he understood that he would need to go to Shimotsuki after he got rid of the Arlong pirates so he immediately scanned the islands with his observation haki. Even though Miles couldn't see into the future with his haki yet he was still proficient enough to search everywhere in a 100 Km radius. He found Arlong's ship stopped about 25 Km away preparing for the invasion of Conami.
At this point, Miles was contemplating what he should do next.
'Should I just teleport over there using my space-space fruit and kill them, or should I wait for them to get here and take them down with the girls? If I take them down now the girls wouldn't need to kill anybody until we start our journey as pirates, but on the other hand, they could get some real combat experience and would not hesitate to take a life if needed in the future. *Hmmm*'
{I think you should go with option 2, If you want them to survive in this world they need to be willing to kill just like other pirates and marines. This is not just a manga or anime anymore, there are things and people much worse than Arlong in this world.} Chloe said in a rare serious tone.
'You're right, I was leaning towards option 2 as well.'
What Chloe said about things much worse than Arlong existing was very true. On earth crimes such as robbery, r*pe and murder were all prevalent, but here it was much worse, especially since the corrupt world government was in charge here and justice freaks like admiral Akainu existed.
'I really should kill Akainu.' Miles thought with a chilly face. Miles hated Akainu the most because he killed his favourite One Piece character of all time, Ace.
{I suggest you hold off on attacking a marine admiral for now. Currently, you have the strength to beat a warlord like Doflamingo, but even with that much strength, you don't have a snowball's chance in hell to kill an admiral.}
'I know that, do you really think I would be dumb enough to pick a fight with an admiral right now?'
{Maybe?} She said with a light chuckle.
'I'm not talking to you for the rest of the day.' Miles said with a monotone voice, unamused by Chloe's mocking comment.
---
"PIRATES!" Someone yelled as he ran through the village.
"It's the Arlong pirates!" Another person said in a panic.
"Arlong!? It can't be" A women said dropping the basket of fruit she was holding and running away.
"Then... that rumour about the fishmen pirate crew in the grand line splitting off... must've been true...!" A man said as he was backing away slowly.
SHAHAHAHA! GREETING, MY BELOVED PATHETIC HUMANS! FROM THIS MOMENT HEREON, THIS VILLAGE... NAY THIS ENTIRE ISLAND SHALL BE UNDER MY CONTROL!
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