Parallel processing AKA parallel thought. One carries out two or more thought processes simultaneously. Since Hikaru has an extra brain albeit tiny (about the size of a small bean) he can divide any workload by half.
This allowed him to easily multi-task in a fight. Having an extra brain made it easy to control all of his tentacles and have time to think. One part of him was focusing on the fight while the other was watching himself fight to strategise accordingly.
The fight felt like a breeze as he had tons of thinking time. It was like taking a seat in one's mind and observing the situation, this was similar to an out of body experience.
While he was fighting, he had heard Hiromi starting up an engine. The sound had gotten louder as she drew close but it was too late. She watched Hikaru slaughter her mother and father at the same time with one strike.
She was terrified but knew that she probably won't be able to outrun Hikaru and so leapt upstairs. As she was in the air, she landed while striking vertically, taking advantage of the momentum from the jump and gravity pulling her down.
Super dense bones sprouted from his upper body and closed themselves around his front like a giant ribcage.
Her chainsaw bounced off from his dense shield but she pressed it back down. White smoke rose from where the chainsaw was cutting. Hikaru's rib armour was being sawed at a fast pace. The bone powder was being expelled by the grinding of the chainsaw producing a small fog around them.
Hiromi had a disbelieving look on her face. She just needed to crack the rib cage open and slice Hikaru to pieces. It seemed too easy. In contrast, her family struggled to resist him. It wasn't in vain; they were pawns to her and pawns were best used when sacrificed. They had unknowingly secured her survival. Her disbelieving expression changed to a sadistic grin.
She had sawed half the rib bones. She could see Hikaru's exposed head and calm demeanour. His stoic but slight smile kept him looking handsome. It was admirable that he could act so calm.
She learnt another of his traits and felt her affection towards him grow. She thought about sparing him and making him her boyfriend but decided against it as he was too strong and could kill her any time.
*Sigh*
She was missing him already. Seeing that Hikaru was so useless and paralysed by the chainsaw, she quit cutting the rest of the bones and swung at his head in a lopping motion.
*Clang! *
The chainsaw was stopped by a bone that was Hikaru's arm. It had a metallic sheen and was shaped like a sword. It was very rough looking but Hikaru had coated a bone in metal that he had absorbed from his victims. Some of the metal came from keys and other random objects that were in the pockets of the people he absorbed. Others came from jewellery, dental fillings, metal implants like hip replacements, etc.
Hikaru wasn't panicked because he could have easily stabbed Hiromi in the neck like her mother but didn't because he wanted to test the strength of his bones for defensive and offensive capabilities.
Seeing that his enhanced bones couldn't handle the power of a chainsaw, he wanted to test weapons manufactured from inorganic materials.
Hikaru's makeshift sword gleaned with a variety of colours like gold but were mostly shades of grey or black, indicating that it was an alloy of many different metals.
The sword had a much higher resistance than his bones as shown by the time it takes for her to grind it. Still, she cut through the layers of metal and struggled at a layer of titanium but that eventually broke too.
However, the chainsaw wasn't cutting smoothly anymore. A closer inspection showed that the teeth of the chainsaw were worn out from grinding against the sword. It wasn't effective on Hikaru's bone layer anymore.
Concluding this, he grabbed the chainsaw with his right hand. He was wearing a handguard made of bone and so wasn't afraid of injuring himself.
*Crunch*
He crushed the blade of the chainsaw by squeezing his hand. Little metal shards glittered in the air as they fell to the ground. Hiromi stared dumbly at the glitter on the floor that was a chainsaw blade with a gaping jaw. Her last hope and salvation were crumbled to tiny pieces before her feet.
Hikaru then kicked her in the belly. She broke the handrail as she fell backwards from the first floor to the ground and smashed the dining table as she crashed.
Hikaru stab-hooked Luffy's body with a spiked tentacle and dislodged it from the ceiling. He took it in and did the same to Juro and Mami. It took three seconds each to absorb their bodies for a total of nine seconds. Hikaru grew a set of wings and gently flapped his way down through the gap in the handrailing.
He was far from mastering control of the wings but with his second brain, he was able to learn much faster and be as good as Luffy without practice. The mental load from using the wings was halved when he used parallel processing.
Hiromi watched in horror and shock as Hikaru floated down with Luffy's ability. She had just seen the wings on Luffy's back melted into Hikaru's body. Now he was flying as if it was completely natural.
He was a parasite that could get infinitely stronger! She had zero hope of fighting her way out of this. Instead, she prayed to the deities that Hikaru will have mercy on her.
She got up on her knees and bowed with her forehead touching the ground.
She spoke the second Hikaru's feet touched the ground.
"I surrender!! Please spare me!"
Hikaru smiled.
Perhaps this was perfect timing. Despite how strong he has become; it was unlikely that he could accomplish his goals solo for the time being. He grew confident as he got stronger but he knew not to be conceited. He had to be cautious as the possibility that there were people stronger than he was high.
Unknown powers were lurking in the shadows. How strong were the high-ranking parasites like the officers? What technological marvels do Architects' wield? Even if no one individual was stronger than him, even he could be killed by small fries as long as they greatly outnumber him. He wasn't strong enough to take on Earth's military alone after all. He needed his army.