A Powerfull Assassin On Parallel World Become Demon Lord?!

The pleasant aroma of grilled meat and soy sauce wafted through the air. There was a thirty-odd-year-old lady standing in the kitchen. An apron wrapped around her waist and her hair tied back in a ponytail.

The woman, Nanase Kiyotaka, was busy preparing a meal skillfully. However, her heart was filled with anxiety and endless worry.

After a moment, the sound of footsteps could be heard heading down the stairs. The one who comes was her husband, Shinichi Kiyotaka.

"Dear, why you have a sad look at your face?"

"Are you really need to ask? Your son was missing and you expect me to act as if nothing happen?"

Her tone was slightly higher and clearly, she was disp.l.e.a.s.u.r.e with her husband's attitude.

"That's not what I mean but you can't show your sad look to Kosaki. We already promised that we need to hide the fact about our family's dark secret."

"She was still in her school due to her club activities."

"She will arrive soon, so please hide your sadness for a while dear."

Shinichi comes closer to Nanase and hugged her. They thinking about their son who'd vanished without a trace.

It had been three days since Ryuga departed from Japan to do his mission. Normally he would back after two days as he mentioned in his message, but he suddenly vanished when he crossed the ocean.

Vanish...

Ryuga wearing a high technology Nano-suit, installed with many gadgets and features to help him during his mission. There was also a GPS system to monitor his position, but yesterday he completely vanished.

No matter how much they looking for him, they never find him anywhere. Even when he was sinking to the bottom of the sea, the GPS will show the accurate coordinate of his location, but this time, his whereabouts was lost, as if he vanished from the Earth.

There were several theories to explain this situation.

First was because of the malfunctioning of the GPS. This theory is the best possible answer because there were no "perfect" products. They still have a chance to malfunction even Ryuga's nano suit was the best technology ever invented on Earth now. But Ryuga didn't show up until now.

The second was because of Alien activities. The scientists were barely known about Alien's technology. Ryuga probably abducted by Alien since he using Nano-suit. The material of Nano-suit comes from the Meteor after all.

The third was the most absurd theory. Ryuga was transferred to another world. The scientists didn't refute the fact that there was a probability of Parallel World, but they still have no idea how to pass the gate to enter the unknown world.

The fact that Ryuga was missing from Earth made Nanase terribly depressed. He wasn't her biological son, but they were deeply attached. She watches his growth every day, know his habits, preferences and spent many years with him. She knows his dark history and that makes Ryuga didn't show his real self. He always acts to please anyone near him. He wants to be accepted and even he willing to do anything to do that.

"Ryuga, where did you go?" , She softly whispering.

"That boy is wise and strong. I am sure he will return." , Shinichi gives her encouragement but he had appeared depressed too.

He was the one who personally training Ryuga to become an assassin. When Ryuga accepted to become the next successor of Assassin, Shinichi was quite shocked. That time, Ryuga was still very young and yet, he could accept unreasonable demand from him.

He made a hellish training for Ryuga to make sure he ready at every worst scenario. Shinichi wants him to come back alive after every mission. He didn't want to lose "another" son again. Ryuga was the sixth boy that he adopted.

He didn't announce every boy that he picked on the public since they were just a disposable tool. Most of them were unable to continue the intense training from him. He selected the best kid and make him become Assassin but sadly they always losing their lives in the mission.

Kosaki was very happy when she meets with her "brother", but she immediately depressed when she knows her brother was gone forever. Shinichi always hides the cause of the death of her brother.

That repeated for 4 times and Kosaki ended up very traumatized because she losing her brother every time. In the end, she just putting an act to pleased her "new" brother. She didn't want to taste the bitterness of losing her brother once again.

This time, Ryuga was selected as her brother. Even Kosaki just acting nice to him, but he accepted that as her sincerity. Ryuga who was starved for love from his family would accept the kindness even they were fake. He living to get that "love" from his new family.

Ryuga miraculously survives in every mission with satisfying results. He never failed in his mission even a once. He always comes back to his family unscathed even without his Nano-suit.

In Shinichi's eyes, Ryuga was a very brave and strong child. He was very m.a.t.u.r.e and composed in every situation. His calm demeanor even makes Shinichi slightly scared of Ryuga. He never shows his expression and no one could know what inside his head. His existence is like an absent-minded sharpened blade. If Shinichi made mistakes when raising him, he undoubtedly will suffer massive damage from Ryuga. Even Ryuga always followed his instructions, that doesn't mean he will do anything he wanted. Shinichi clearly grasps Ryuga's ability when they spent time together in training. Ryuga is very smart and always think rationally. His love also very strong toward his family and Shinichi knows how to use that to keep Ryuga "under control". He doesn't want Ryuga to harm his family, so he provided a warm family for Ryuga.

In Nanase's eyes, Ryuga was adorable, cute son. He always living up her expectations. He never rejected her request. He was excel in studying, even teachers in the school were praising him. That makes her very proud of Ryuga. At first, they met, Ryuga's eyes were like a dead fish, devoid of any emotions. His mind was filled with 'how to make me useful, so they won't abandon me.' .When she knows that, she hugged him firmly and cried. He was too young to think about that. She slowly approached him and learn everything about him. She clearly remembers his expression when he ate her special fried rice. Ryuga was cried for the first time when he living with Kiyotaka Family. He apparently remembers when he had dinner with his real parents in the past. Ryuga slowly began to change. He learns how to initiate a conversation with the family member. He wasn't shy to make conversation but he felt like an "outsider". He knows his limit and his place as newcomers, so he didn't want to act over-familiar. To Nanase, Ryuga was truly a blessed child for her.

As for Kosaki, Ryuga was the best brother she ever gets. She already witnessed her "brothers" died several times and leaving her alone. They always promised to stay with her forever, but they were lying to her. Not only Ryuga always stay on her side, but he also protects her when she needs it. She always bragging about it to Nanase and Shinichi every time.

"If we tell this to Kosaki, how will she reacted?"

"I don't know how to answer you dear..."

Obviously, Kosaki will be shaken when she knows the truth. Nanase and Shinichi could only be praying for Ryuga to return soon.