Demon Lord's Reincarnation

Hilda, Milly, and Kurt were out on the road heading towards the Capital city of the Serbek Kingdom, Varzon. Unlike the time Lara sprinted towards New Grenton, Hilda and her party needed to move slowly. It was a good thing that Hilda was a very experienced adventurer, which made traveling much easier. In their current pace, it will take them around nine days before reaching Varzon. 

...

While they were traveling Milly was reading Kurt the book Ren gave him. The instructions in the book were very precise, and the explanations were quite simple. Seeing how simple it was, Milly felt confident that she would be able to teach Kurt a few things from the book.

The first step was to learn how to sense mana. Ren had written different ways on how to do this. He didn't know which way would suit Kurt since he hasn't properly seen his little brother. So with so many choices, Milly decided on one which felt like something Kurt would understand. 

"Kurt close your eyes." Kurt did as he was told. "Now imagine butterflies flying all over your body. Do you see the butterflies?" 

"Mommy, I see them." 

"Do you feel the butterflies flying through your body?" 

"I do," Kurt got excited as he noticed the weird flow in his body. To him, it was a ticklish sensation. When Hilda and Milly felt the tiny bit of mana Kurt was emitting they immediately knew that Kurt was able to make his mana flow successfully. 

Mana would naturally start to flow through one's body at the age of six, but it was better if you're able to force it out before then. Now that Kurt had successfully activated his mana flow before he reached the age of six, he had a huge head start compared to his peers. 

'That book is amazing.' Hilda looked at the book bewildered. She already knew what kind of nonsensical existence Ren was, but somewhere in the back of her mind, she didn't expect that his book will be all that effective as teaching material. Since Ren was someone who felt like he was naturally strong, so teaching others doesn't feel like something he would be good at. 

It was a good thing, Hilda didn't know about how Ren trained both Valdel and Lara, if she did she might have a difficult time accepting it. 

On the other hand, Milly was excited to see her son activate his mana. She wanted to see how far Kurt could go. So after that day, Milly started teaching Kurt new things from the book Ren gave. Even though Kurt wasn't able to comprehend much, he still found it fun to listen to. 

Ren had written the book in a way that it doesn't sound like a training manual, instead, it felt more like a story. A story in which the hero who started out as a helpless child turns into a reliable warrior mage. In each chapter, the hero would go through a new training regimen which made him stronger. 

It was obvious that the training in this book was teaching Kurt to do the training depending on his age, like the hero in the book. As the hero grows older, the sets of his training increases and changes. Milly was supposed to teach Kurt only up to the fifth chapter, where the hero was still three to four years old. Yet due to Kurt's curiosity, they started reading the parts they weren't supposed to read yet. 

'Still, even though Kurt doesn't understand these parts yet, I guess knowing about it should be somehow beneficial.' They were already halfway through the book, and Kurt was really excited by the warrior mage character in the book. 

"Mommy, can I be as strong as the warrior mage?" 

"Of course you can be, as long as you continue to train someday you will become as strong no even stronger than the warrior mage." 

Hearing her mom's answer Kurt got really excited. Their journey continued without much of a hindrance. There were occasional monsters and bandits, but with Hilda's current level those didn't prove to be a problem. In fact, even Milly could have easily handled the situation.

They were now halfway through their journey. Even though the trip could be easier if Hilda carried Kurt and she and Milly started running, by doing that they would arrive at half the time. Still, using this time to teach Kurt a bit about the contents of the book, was a good thing, so they decided to slow down their pace a little bit. 

...

After traveling a week more than they initially planned, Hilda, Milly, and Kurt finally arrived at the capital city of the Serbek Kingd, Varzon. As Kurt was getting excited to enter the city, Hilda suddenly unsheathed her sword, twisted her body, and attacked whoever appeared behind them. 

The person who stood behind Hilda easily caught the strong sword slash with his bare hands. The person then grinned. 

"To be able to sense my presence and attack, you've gotten stronger Hilda," Ren spoke while grinning from ear to ear. When Hilda saw Ren, she held back her tears as she let go of her sword. With swift movements, Hilda was about to hit Ren with a slap, yet as expected from Ren he easily evaded. 

"Why are you trying to slap me?" Hilda continued trying to slap Ren, but Ren continued to evade each strike. 

"You dumb idiot, just stay still and receive your punishment!"

"Punishment? Punishment for what?" 

"You left so many people worried about you, and you didn't even bother to tell us that you're still alive. We were all worried about you!" As Hilda screamed the last part a resounding slap echoed throughout the area. Hilda was surprised that she was able to hit actually Ren. She looked at Ren whose face didn't even move a centimeter despite getting hit by a powerful slap. He was looking at Hilda with such a serious face. 

"You do have a point, I guess my circumstances are nothing more than excuses. I apologize for making you and the others worry." Ren hugged Hilda who started blushing furiously as she got confused by the sudden shift of events. 

Once Ren was done hugging Hilda, he looked at the two other people present. Milly was just standing there holding Kurt's hand. She didn't know what she wanted to say and was still in a state of shock. 

"It's been a while mom." Hearing his voice that was calling her mom, Milly could no longer hold it in as she ran towards Ren while holding Kurt's hand. She immediately hugged her eldest son and continued to cry on his chest. 

"Thank you, Ren, thank you for staying alive."

"It's alright mom, even if the very heavens fall I'll be sure to lift it up. I won't be dying just yet." Ren jested as he hugged his mom until she was able to calm down. 

...

Once the two women were done crying, Ren shifted his attention to the little boy that was glaring at him. 

"Oh, why the sour look on your face?" Ren asked Kurt. 

"You're a bad person, you made Big sis Hilda, and Mommy cry." 

"It's alright Kurt, he didn't make mommy cry, in fact seeing him made me very happy."

"Really?" 

"Yes, let me introduce you. This is your big brother Ren." 

"Big brother?" Kurt looked at Ren. The big brother he was imagining was something like those heroes in the picture books his mom read to him. A handsome, charismatic man that had the sun rising at his back. Yet the big brother in front of him was an average looking person. 

"Yeah, I'm your big brother little Kurt. I see that you have already read my present, so did you like it?" 

Kurt hid behind her mom and stared at Ren without answering. 

"No need to be shy Kurt, your big brother is not going to eat you." Milly gently smiled at her youngest son. Kurt once again peeked behind Milly's back to look at Ren. 

"Are you really my big brother?"

"Of course, how can I prove to you that I'm really your big brother?" 

"Mommy and all the big sisters say that my big brother is the strongest of them all." 

"I see, so you want to see my strength. Very well, open your eyes wide and witness how strong this big bro of yours is." Ren gathered Spirit Aura into his fist and casually punched at the nearby trees. The power of the strike pulverized the nearby trees. When Kurt saw that he couldn't help but get excited. 

"Wow!" 

"So do you believe me now?" As if his reluctance never existed in the first place, Kurt quickly ran towards Ren. "Big Bro can you show me more?" 

"Of course, as much as you want." Ren then started to show Kurt different feats of strength. Like carrying a boulder and crushing it. Every time Kurt saw his big bro show off his strength the more excited he got.. In but a few minutes, Ren had successfully made his little brother like him.