"I wonder if she became a maid willingly," Erix wondered before shaking his head. "Whatever, let's head inside and absorb the remaining cores we are saving."
Rin entered inside with a chuckle and said, "I had a reason to save those twenty cores."
She turned around and pulled Erix's collar before kissing him and closing the door behind her.
Although surprised, Erix cooperated as their tongues and lips played together for a few seconds before Rin smiled, her beauty and love for him always making Erix high.
"What now, my lady?" Erix smiled.
"It's time for the surprise. And first, we'll have a bath."
...
Since the bathroom was big with a four-meter radius round bathtub and plenty of ground aside from that, Rin decided to reveal her surprise there.
Sittin' beside each on the edge of the round bathroom with their legs in the water, Rin said, "Take out the cores and put them here."
Erix did as told, eagerly waiting for the so-called surprise.
"Now, just follow my lead," Rin grinned and fluidly sat before Erix on his lap, pressing his pulsing stiff cock under the pink slit of her pussy.
She then picked up a core and said, "Pick a core and start absorbing it."
"Alright, but before that-" Erix said with a smile before he held Rin's waist and adjusted her up a bit, causing his meat rod to slip into her pussy. "This position is better."
Rin felt a wave of pleasure as Erix's cock gently hit the end of her pussy. She smiled in a drunken allure and said, "Now, the next step."
"Absorb the core, channel its power to our reproductive organs, and combine both of them."
"Oh?" Erix was surprised.
"Just do it," Rin said as she quickly absorbed the core's energy before the dim crystal turned into motes and vanished.
Afterward, she wrapped her arms around Erix's neck and started moving her hips slowly, causing Erix's pulsing meat rod to feel the pleasure of her pussy that was perfectly suitable for his dick.
Erix let Rin move on her own as both of them savored the ultimate pleasure.
Doing as Rin told, Erix also absorbed the core and said, "I am ready."
While moving in a slow rhythm with a tantalizing smile and her breasts getting fondled by Erix, Rin said, "That mysterious woman said that this method is only possible because you are half-undead and half-living. Follow what I say and see the magic."
"Channel the core's energy we absorbed to our reproductive organs and combine them with me."
Erix did as told with anticipation and pleasure gleaming in his eyes.
'Double! This core belonged to a level 63 monster, so it should generally give us 3 magic and 7 mana, but...'
Seeing Erix's shocked expression, Rin kissed him and chuckled, "It's great, right?"
"It's fantastic!" Erix laughed, his expression thrilled. "We'll be able to max out our magic core's limit in a day or two with this!"
"Do you know why this is possible?" Rin said, an affectionate grin playing on her lips.
She continued with her answer, "Because of your undead source. That mysterious woman told me that you have an undead source because of being Zombie, and that source mixed with your living soul, so it gave you a unique existential force."
Erix was startled. "Unique existinal force?"
"I don't know what's that, but that's what she told me. She said that this force is not fully developed yet, but it's faintly present in the primal energy of your body, which is none other than your semen. So you can use it with this special skill to boost the core's energy for better returns."
Rin then shared the skill with Erix.
"I am sending you the extra skill rune she gave me."
[Magic Symphony of Essences]
_Type: special skill.
_Use: Combines two compatible sources of powers, one as a base and one as an addition, for unknown results in the direction of a source used as the base. The cost of mana depends on the mana required to combine the sources seamlessly.
"Great skill. Let's go for the next round," Erix grinned and kissed Rin.
"We'll absorb five cores at once this time," Rin smiled as she picked up five cores and chained them with a point of mana before putting them around Erix's neck.
"Nice idea," Erix commented upon seeing Rin making a necklace of cores.
She also wore one before wrapping her arms around Erix and pulling his face to her bosom.
"You really like having your boobs sucked, eh?"
Rin rolled her eyes and rubbed her erect pink nipples at Erix's lips, "It's because you made me get addicted to it. Whose fault do you think it is that my size is increasing to E?"
Erix laughed and put one breast in his mouth before using her tongue to play with her nipple, "They are perfect for me."
Rin giggled as she was feeling both pleasure and comfortable tickles, "Do it moderately so we can also focus on absorbing the cores."
"As you wish, my queen."
...
The duo had power-up using all cores and intensely pleasurable fun for the next three hours before they finally felt hungry and called Lira after getting out of the bathroom.