Unlike Tsubaki and Saji, this time, they didn't dare to follow when Riser asked Sona to follow him.
Naturally, Serafall was an exception.
"What are you going to teach Sona-chan, Riser-chan~?"
Latching onto his back, Serafall asked that question curiously. She had been following him, listening to all of his teachings in silence as she was extremely shocked by his knowledge.
Sword techniques, martial arts, inventors, creative minds, genius trainers, etc...
Serafall knew that it was wrong, but somehow, she wished to have his child right away. After she saw the death of Sirzech, she knew that anything could happen in this era when God had passed away.
Serafall didn't wish to have regrets and thought that... even if she might cause sadness to her little sister, she wanted to have him.
Moreover, it wouldn't be bad to share a man with her little sister.
However, what does Sona think?
Serafall peeked at Sona, but Sona's eyes had always focused on her husband, completely enraptured.
"...."
While Serafall was speechless, she also didn't feel surprised, especially when she had watched Riser's steps from nothing to now.
After that divorce with Rias, who would have thought Riser could become Lucifer?
Yet, it was also because of this reason that such a man was just too fascinating!
"How long are you going to follow us?" Riser glanced at Serafalll.
"...."
Serafall pouted and threw a tantrum. "Riser-chan is a bully~! Hmph~! I won't talk with you~! Hmph~! Hmph~!" As she folded her arms, causing her breasts to swell even bigger, she looked away but kept glancing in his direction from time to time.
"....." Riser and Sona.
"Still, I have never asked you this before, but have you ever trained to become strong, Serafall?" Riser suddenly asked.
"Er..." Serafall thought for a moment, trying to remember whether she trained or not. Unlike her youth, she had been busy with many things, such as her magical girl show and her job as Leviathan, so she hadn't trained for as long as she remembered.
Whether Riser or Sona were in a hurry, but the two were quite speechless by Serafall.
"No?"
"...um." Serafall nodded. "It seems that I don't train?" There was a question mark on her words, but she couldn't be blamed. After all, the last time she trained was before the Devil Civil War. It was some time before she was still the heiress of the Sitri Clan, and at the time, she couldn't even imagine that she would become Leviathan.
Riser nodded and didn't feel surprised. The majority of strong beings were like that as they became strong the moment they were born in this world. They might have trained, but they didn't train with an obsession like Sairaorg. Moreover, there was no need for them to train since they would become stronger as they grew older, especially when their pedigrees were the best of the best.
It should be the same case as Sirzech, as he was strong from the moment he was born.
However, his wife differed from Serafall, and Sona needed time to train her strength further.
"Before I train you, how about you show me how you fight first, Sona?"
"Okay?"
"Hey, is that all? Why didn't you ask me more? So-chan! Riser-chan! Don't ignore me~!"
However, Riser and Sona were focused on their spar, yet even if he said that it was a "spar," it was nothing but a demonstration, and to be honest, Sona's power was weak. He knew that he was quite cruel to say this, but the innate ability of the Sitri House didn't have much of an advantage over the Underworld.
The power of the Sitri house was the power of water, and in the Underworld, where there was no sea, they could only rely on either lake or river. With that limited amount of water, they could only rely on their Demonic Power, but creating water with their Demonic Power was simply arduous, and no doubt such an act would drain their Demonic Power excessively.
Moreover, unlike other elements such as fire or lightning that could damage their opponents easily, one needed a large amount of water to cause damage to their opponent.
To be honest, in terms of firepower, Sona was weaker than Rias, who inherited the power of destruction.
Watching Sona, who created a large serpent of water and then smashed it into her husband, Riser didn't do anything and just let this attack hit him.
While Sona hesitated, she gritted her teeth as she knew her husband was the strongest devil, but even so, watching how her attack was easily solved by being boiled and changed into steam while doing nothing, she was at a loss.
"Don't stop. Keep attacking me. Don't hold back and use all of your attacks on me!"
"Yes."
Sona answered as she showed amazing control over her water manipulation, creating a variety of beasts that charged toward her husband in various directions.
Riser didn't move like before and just clad his body with the armor of flames, causing all of Sona's attacks to turn into steam. He nodded as he understood Sona's level.
"Riser-chan is a bully~! Don't bully Sona-chan, Riser-chan~!"
Serafall, who was on the side, felt her little sister was bullied by Riser, but neither Riser nor Sona paid attention to this woman. Sona kept attacking him until he told her to stop.
However, Riser ignored Serafall since it wasn't his first time to bully Sona, especially on the bed since her reaction was too much, so it couldn't be helped, right?
"Okay, stop, Sona."
"Okay."
Sona stopped, and her breathing became heavy as she used a lot of her Demonic Power to attack her husband previously. If she was against another opponent, she might not have shown such embarrassment, but facing her husband, the strongest devil in the Underworld, she needed to give her all, so her consumption of her Demonic Power was intense.
"Sona, your technique is amazing. There is no doubt that your mastery of your power should be several times higher than Rias."
Riser had no doubts about this matter, as he knew Sona's mastery over water manipulation was higher than anyone's. If he made a comparison, it was like Sairaorg's mastery over a physical ability.
"Thank you." Sona was happy, but she was smart and knew that her power was nothing compared to her husband and her older sister.
"However, you shouldn't limit the development of your power."
"Limit the development of my power?" Sona was confused. "What do you mean, Dear?"
"I mean... is all of your attacks about shaping water into a certain form, then bashing it into your opponent?"
"Yes." Sona nodded naturally.
Riser took a deep breath and fell into silence, but only then did he realize how monotonous and uncreative the devil was, but maybe it was all due to their long age that they didn't long for change, and with their power; it was enough for them to rampage, yet it was also because of this that nothing had changed after a long time.
An angel who had a light manipulation ability would only shape it into a spear and then throw it into someone.
The fallen angel also wasn't much different and only changed the color of their light manipulation with colorful and funky colors.
Even Sirzech, while he was said to be the strongest, did nothing but use the power of destruction.
Sona and all the members of the Sitri House should be similar as they would only use their water manipulation to bash it into their opponent.
However, Riser also couldn't complain much since his family was the same, and before he got to the system, all he did was just create a bigger fire to fight his opponent.
Yet, this mistake could no longer be tolerated.
Sona was his wife, so Riser was going to teach her.
"Sona, have you heard about the water phase change?"