The vessel that he is

Usopp was sitting along with the three kids who were now his crew. Their names were weird as they were literally vegetables in Japanese- Ninjin, Tamanegi and Piiman.

" You guys will be known around the village as the notorious vegetable trio of the invincible Usopp pirate crew. I will be training you without mercy! Got it?"

Usopp ordered them while still managing to keep the face and actions of a man who was used to boasting. He also had further plans for these kids later on since he would require them to act as his punching bags and helpers for many matters he had planned. He also would make them follow a proper train schedule so that they would be strong enough to take on a normal East Blue pirate crew because there would be no one to protect the village after he left.

"Yes. But don't hurt us badly or we will tell our parents"(Ninjin)

"We want to get strong and succeed in achieving our dreams, but we won't accept too much tyranny!"(Piiman)

"Uhmm, Exactly. We will accept your orders but will also make use of you too!"

Said the three kids, who were awfully grown up for their age. Usopp was scared out of his wits when he heard them and their logic, which somehow felt like he was thought of as someone who could lead these children onto a proper path. He doesn't understand that his actions had made him a trusted individual for his creations and thoughts, although it was reduced a lot because of his 'i am the only witness' type stories he spun.

'These kids are cute in some ways huh. Let me use you and also be you oniichan and captain.'

Thought Usopp as he dismissed the crew's activities for the day. As night fell, Usopp thought of new ways to increase his potential, as the training he does in his younger age would be a major contributor for becoming a powerhouse.

...

[Pirate Era Year 20]

A few kilometers away from the Gecko islands, underwater. The area became a major spot for Usopp's training since the time he found out that he could focus his senses better while training underwater. It also helped him reduce the flaws in his movements and create shooting and fighting moves that could exert force on different occasions.

'This is hell! The pressure changes because of high speed movement underwater and the sensory overload is killing me. But because of it, i am close to activating my color of observation and might awaken it naturally like the trained activation of the nen ability.'

Our protagonist was currently strong enough to take on a vice admiral in combat, although he did not think he can defeat them. Because of the underwater training of strength and shooting techniques his body was as strong as Luffy's peak strength before the time skip. He also had some underwater 'fighting' experience, when he attacked small sea monsters from a long distance. He was basically bullying them and he loved it.

...

Syrup Viilage, Kaya's Mansion

'It has been a while since Klahadore was appointed as a butler. I also heard that Kaya was ill. Even though I had been to her place to lie a bit, I don't know if I can cheer her up. But it is not impossible with my knowledge of anime and novels. Please god let this work so that I could make her fall for me!'

Our protagonist was bad at relationships. No, he was bad at making women laugh. Even worse, he actually liked her even though he only talked to her very briefly. It was as if he found someone he had to protect and love, and never give her to anyone else.

'Now I have to make a good entrance. Where is that damned window now?'

He found the window and sneaked over to that place, avoiding the minor irritation that is Klahadore. He then threw a few pebbles at the window and when the window opened, out came an angel!

"What are you doing up here, Usopp san?"

Her face and her voice felt ethereal and divine, as beautiful as an angel. Or so it seemed in the eyes of our protagonist, whose thoughts were painted completely in pink.

'God damn it, she is cute! Now make a proper dialogue sequence worthy of the Captain of the Usopp pirates.'

"I heard you were looking gloomy these day, Kaya! I cannot overlook such an important matter on my territory! This Great Usopp will cheer you up with the stories of my great adventures!"

Thus began Usopp's days of caring for Kaya, making her more cheerful and bringing her closer to him on an emotional level.

...

'All I have to do is wait for my color of observation to awaken and prepare secondary measures for any unforeseen situation. Soon my adventure will begin. Though I will kill that bastard Kuro if he dares to harm Kaya!'