Rein was only 17 years old at that time. He got caught up with an evil organisation and got busy with getting rid of them with her two lovers Stella and Tasha. While going after this organisation with a very deep root, they found themselves in a small nation called Ucarioka.
Ucarioka was not an important nation by any means. But it was quite a remote and desolate nation with most of it filled with empty grassland. For that reason, the evil organisation had found this place to be extremely suitable to act as their hidden headquarters.
But the main reason why this place was their hidden headquarters was because the big sister of the leader of this organisation was living here with an extremely valuable item which was given to her by her father.
The leader wanted to get his hands on this item for a long time, but a fate type spell cast by his father was preventing him from getting it as trying to get it by force would just destroy the item.
But he had managed to find a loophole in this security system. And that was if the sister died naturally then the effect of this spell would disappear. For that reason, the leader secretly forced his sister to be exiled in the remote countryside to face hardships.
But unexpectedly the sister started to enjoy the laid back life in the countryside and was nowhere near her death.
The leader was getting impatient with it and took a drastic step to reduce her lifestyle to be bare minimum and forced her to eat unhealthy and poisonous items by controlling the food she could get her hands on.
This plan was effective and very soon the poor sister was on her deathbed. She was taking care of a girl who was like her daughter and was also getting poisoned alongside her. The sister was extremely sad after understanding the whole situation but it was already too late.
She knew that the little girl she was taking care of was special. And just as she expected, the poison that almost killed her had no effect on her body. Even when she was dying she was unwilling for her evil brother to succeed in getting the item she was protecting for her whole life.
So, she made the very last request of her life to the girl. And it was a simple request of safekeeping an item without risking her life. The sister also told that girl about her own life and also mentioned that she was always burdened with the responsibility of protecting this item.
So, now that she was going to die, suddenly she was feeling very light and free. She was happy with her life and happier that she got a daughter like Celestine. Her name was Carmelia and she was Celestine's only family before she met Rein.
...
After Carmelia died that evil organisation tried its best to get the item at any cost. Many assassins and thieves attacked Celestine non-stop but all of them were killed by her inherent special ability.
As the personification of world calamity, it tried to destroy everything in its vicinity and unfortunately the village where Celestine was living for the last few years was the closest settlement and her own summon was going there to destroy her home.
Just as Celestine was feeling true despair, Rein appeared before her following the trails of the evil organisation and witnessed this scene. He asked Celestine for a solution and told her to get a grip. Then he used his Eye of Truth to analyse this monstrosity to find a solution.
As soon as Rein used his Eye of Truth on it, he froze in fear. For the first time in his life, he felt like a small ant in front of a dragon. He had never seen anything stronger than this monster before him.
At that time, Rein was barely a blue grade transcendental person if he was judged by his system that he created later on and was no match for the monstrosity.
But he hardened his heart and was able to think of a solution. He found that the reason why Celestine was unable to unsummon it was because it was actively resisting that. So if Rein could hurt the monster badly enough to make it lose focus, then she might be able to unsummon it.
Rein told the plan to Celestine but she was unwilling for anyone to risk their life for her. But Rein assured her with a daring smile and promised to come back to her safely.
Tasha and Stella were currently not with him as they were destroying the evil organisation and that was a happy thing for Rein as he did not want his precious lovers to face this thing.
Rein used all his powers to boost the destructive properties of the lightning which was coating his sword. Her also covered his feet with crimson lightning that were over boosted with the speed property. Then he did an all out attack in the calamitic monstrosity.
Rein's all out attack was not strong enough to even hurt it badly but it was definitely enough to make it feel pain for the first time. It immediately focused in Rein and swept him away like an insect.
But this much was enough distraction for Celestine to be able to cancel the summoning and the monstrosity disappeared.
After that Celestine went straight to where Rein had flown to and saw an almost dead Rein and hugged him with a tear filled eyes. Rein was very badly hurt but as long as he was not dead, he was confident in getting well in a short amount of time with his skill.
He said that much to Celestine to reassure her and also asked her to not cry as it did not look good for a kind beauty like her.
Celestine sat beside Rein for one whole day as that was the amount of time Rein needed to heal up. They talked a lot at that time and soon love blossomed between them.
After getting perfectly healed, the first thing Rein did was to propose to Celestine and she accepted it immediately. And that's how Rein became the son-in-law of the world itself.