Darui is a money loving bio-researcher. Although he loves money his thirst for research is no less. He is called a fanatic and mad scientist from the people who know him but he preferred being called a 'rational scientist'. Although he didn't consider anything but his research and money. He used to create and sell tools occasionally to underground organizations for money to further progress his research.
He sincerely believes money is the key to innovation and hence made huge amounts of money to further his research in the field of DNA manipulation. It was banned and even abhorred at the mention of it in most countries. So he couldn't do anything publicly so he used his underground connections and bribing some officials to setup a lab in Coit port town.
A port town is comfortable because a lot of goods move through the city both legal and illegal. It was easy because most of the Govt officials are corrupt. Then he occasionally used his connections to fetch a few orphans to experiment on. He was failing continuously but each time he was getting closer to his goal of 'Strengthened Humans' by fusing a human with another person's DNA.
In his last experiment he managed to retain the face of the person despite the rest of the body became useless. So, he was pretty hopeful and was very happy to be making decent progress in his research. He was looking forward to today's test, then it happened roughly 1 hour before the test the lock was broken for the Cart which carries the test subject(a child). It was a lock which alerts when unlocked or broken. Unless you got a very high chakra sensitivity you'll not be able to notice.
He realized some rat sneaked in. He went to that floor and realized that the lock was locked again without any commotion. He clearly understood that it's a group attack with one sneaked inside. So, he thought it'll be a 3 man team with a teacher. Since a teacher wouldn't usually prefer sneaking in, he thought it should be a genin. He was careful and logical in his estimates.
He went back to the 3rd floor and thought of an idea in some time. Since, he was gonna experiment he should on the test subject. The place where he places the test subject was an enclosed sturdy glass. It was spacious enough to fit a few people at once, it was done so that group testing can be done faster at later stages. And it just so happened to be able to fit the cart in it's entirety.
He carefully started preparations for the test earlier than normal times. He didn't mention the attack to anyone since he was sure that if mentioned they will not be interested in doing test and even if they did they might make a mistake in tension. He just went ahead with the preparations and checked everything for a while. Then he raised the power of the machine to the highest level despite the objections from other assistants.
At the highest power mode the machine might become temporarily unusable or even permanently disabled after one use. He didn't seem bothered because he needs to move on and build another lab elsewhere because the location was exposed. He didn't hesitate in the least and completed preparations at the earliest.
He then ordered the assistant to get the cart. The assistant went and got the cart from the 2nd floor. He ordered the assistant to place the cart in the target location. As soon as the cart was in the target location he pressed a switch to get the glass from the top to cover the cart. After that he moved behind the reactor and started charging the reactor to shoot. Then the cart broke and he saw a young boy.
Boruto's perspective:
As he was thinking of his plan of action as the bomb he was supposed to throw was missing, He heard the sound of machine whirring to his left. He broke the cart from the inside without a second thought and found that he was inside a round glass enclosing. Then he heard a humble looking gentleman saying "Caught ya".
Darui went on to say "It's an honor to have you here. I'm Darui owner and head scientist of this Lab. You're the chosen one or should I say you've chosen to become the last lab rat for this test. Either way, You're lucky to be of use to me."
While Darui was saying his greetings, Boruto started looking around and found that there were about 10 people. 1 at the level of Konohamaru, 6 at the level of genins and the rest of the 3 seem to be lab assistants and normal people. He thought 'Its hard but still doable'.
As Darui finished his greetings he didn't expect or wait for a response and kept on charging his device and kept looking at screen to make sure nothing goes wrong. Meanwhile, Boruto didn't have the luxury to wait and see the result. So, he tried to hit the glass as hard as possible. It vibrated a bit but it didn't break. Then he tried to take out a kunai and tried to hit it, though there was a mark it was from from damaging enough to get out.
While he was thinking and kept on hitting the same place, his team attacked from 3 directions and got inside. They were surprised and tensed to see Boruto in a Glass enclosing. Since Konohamaru was the closest Sarada and Mitsuki focused on dealing with other people.
As soon as the attack started everyone became vigilant and started to counter the attack. 2 genin levels went towards Mitsuki and another 2 toward Sarada and 2 others started to move near Darui to protect him. Konohamaru went near Boruto and broke the glass which was too hard for Boruto to break out on his own. Boruto got out and Konohamaru said "I'll deal with that guy you deal with others and stop the machine" pointing to the strongest guy.
Boruto nodded and Konohamaru started fighting with the other guy. Boruto quietly went towards the machine and found 2 people guarding it. One of them came forward and started fighting with Boruto. Although he was weak, his movements were swift and he was very slippery. Although he tried he couldn't hit him properly to deal enough damage. He fought an intense battle for half a min and decided to use clones.
As he started using clones the tide of the battle was shifting. But the same couldn't be said for others, Although Konohamaru was able to handle the enemy he couldn't deal a decisive blow to end the battle. Mitsuki and Sarada were also in the same situation, both were holding on but would need a slip up of the enemy or help to break through. Sarada was even severe even though she is holding on for now, drain of using Sharingan started to show as the battle is getting intense.
Boruto used clone, disguise and lightening subsequently to gain the advantage and after a whole minute managed to kill him. Although his comrade is dead the other guy didn't move and just stood near the machine as if to protect the machine and the scientist Darui. The Reactor seemed to be almost charged to shoot, so Boruto rushed to defeat the remaining guy. But the remaining guy is using a technique to shield himself from outside. He made a dome of almost transparent shield to cover him and the machine.
While things were blocked for Boruto. Sarada was losing the fight, even with Sharingan fighting against 2 tough and veterans was very had and they had very good team co ordination. While fighting she finally managed to kill one guy but as she was defending against the powerful blows of the enemy's chain attack. Her legs were getting deeper in to the floor making it hard to move. Then a stray shuriken came from Konohamaru's enemy and hit a huge pillar behind her. Then the pillar started to fall towards her side as she was already troubled by defending against a heavy enemy.