Eren was looking at Nina's butt with absolute interest. Therefore he didn't realize that aunt Nina had turned around.
Aunt Nina was surprised by the kid's change of behaviour. Eren had never shown himself out of focus when he was busy making potions. He would always give his best when learning about potion making from her or when making a batch of elementary potions.
This was the first sign that Eren's lack of sexual education, or to be more precise, lack of sex, was going to affect his personal and professional life. Nina determined that she can't let the kid spiral out of control at this stage when he was going to focus on his career and studies in the academy. It's high time she explains this stuff properly to him.
Nina had already closed her shop for regular patient visits and customers. Even the citizens of Osan were aware of the current situation. So they won't come to her by accident.
Any patient or a customer could be potentially related to the disturbance in the Osan woods. Therefore the Osan Healer's association had requested the healers in the city to stop their personal practises for the time being and focus on potion making while they take care of such entities through the city's infirmary and elementarily established potion bank. Of course, the healers will be granted a fixed pay per day for the loss of their income by the association through the kingdom's and city's joint funds.
Nina decided to wrap today's delivery first before resuming her 'talk' with Eren. She made Eren snap out of his reverie by waving her hands in front of his eyes. That made Eren blush a little as he scratched the back of his head and smiled awkwardly. Then he resumed making the elementary potions' lot that was assigned to him.
A wave of relaxation washed over the duo once it finished up with the delivery. Nina then used her ID stone to contact her source, letting them know that the delivery had been ready for the taking. A goods carriage carrying the insignia of the Osan Healer's association stopped outside Nina's home. When the delivery was loaded on the carriage, Nina and Eren were free for the day. But lunchtime had arrived by then.
Eren made some lunch for both of them. When they had their lunch and Eren was about to head towards his room, Nina stopped him and told him to stay where he was.
Eren looked like he was confused but he knew the 'talk' was going to get resumed. He was excited. This time there will be no interruptions. He had already planned what he needed to do and act by role-playing this scene countless times in his head.
Eren also talked with Reen before he stepped downstairs, expecting the talk to take place today.
Eren had warned Reen that if she fails to stay in her current position until he says otherwise, she won't get the food. Plus, she wasn't allowed to contact Eren until he contacted her. Eren feared what Ren would Reen do if she felt him being sexually excited. She might come out in the open to check up on him, making herself known to Nina in the process. Therefore, he decided that he'll also put their mental connection on hold so that they won't share the feelings.
The poor, always-hungry, demon beast girl named Reen obliged her master's orders without any objection. Her food was on the line after all.
"Erni…." aunt Nina started first:
"I told you we would have this talk before you leave the house for the academy and I think it's about time we do that. The lack of information is surely starting to affect your daily life and it'll get worse in the dorms with so many girls around."
Eren begged to differ. Thanks to being an old man from the past, he knew he wasn't going to be that interested in making out with bratty girls. There was a certain charm in mature ladies that those girls lacked. But he didn't make his opinions audible and let aunt Nina continue:
"Before I go ahead though, I want you to review what was said that day so I know you got those things right." Nina looked at Eren and he nodded:
"I know that the organ stiffens when you think about the butt and it is very natural. I called it a curse and deformity at first but it is a blessing. Most men experience the same thing when they become an adult.
The stiffness can last for a long time if you keep on thinking about the butt. There's some sort of way to make that stiffness disappear but I'm yet to know about it. And it can also disappear when you take a cold shower or get busy with your work. How am I doing so far?"
Eren said all those things with a straight face, oozing seriousness. Nina had to believe that the kid was so shocked to the core by experiencing such a biological phenomenon for the first time that he had studied it clinically, like a test paper in an exam.
Nina couldn't help laughing internally at his remark on the butt. So the breasts did not invoke the same reaction in him. It seemed Erni was a butt guy. He would only experience a hard-on when looking at the butt. She felt a little disappointed in her bosoms. They were naturally much bigger than average but they still failed to garner the kid's attention.
Nina's breasts were left out of Eren's imagination as a neglected pair!
Then Nina gave a self-explanation to herself that Eren just wasn't in the know about the whole subject. Maybe he'll like her shapely breasts with equal fervour when he gets aware of things.
She again criticised her thinking and continued:
"That's mostly right, Erni. Although it depends upon personal preference, one might experience the same stiffness when looking at the woman's breasts. I'll tell you more about that later.
First, let's talk about the difference in sexual organs between a male and a female. The organ that experiences sudden hardness is the male genitalia called a penis. Then there's female genitalia called a vagina. I don't suppose you know about it, do you?"
"Ummm….no," Eren replied with fake honesty. It made Nina continue with her fake sternness as well:
"Female genitalia is quite different from male one. It doesn't have a protruding organ. Well, to be honest, there's one small protrusion in it, but you don't have to know about it for now. A penis gets erected when it is visually or mentally provided with some stimulation. Just like what you experienced last nigh…. Errrrrr… like what you experienced that day. It was your penis getting erect with visual as well as mental stimulation."
Nina tried her hardest to explain to Eren with a straight face what does the erection mean, and how it is used in sexual intercourse. She kept her language clinical and gave him the most basic knowledge about sex-ed. She was about to metaphorically pat her back for a job well done when Eren's rapid-fire round started:
"So aunt, a vagina also gets hardened like a penis when it enters it?"
"Hehehehehe! No silly. How did you even come up with that question? Didn't I just explain to you very clearly how intercourse works? If a vagina experiences the same hardness, how will it allow the penis to enter it?"
Nina couldn't help chuckling at Eren's question. The kid's brain must have been short-circuited by all that intimate information, Nina concluded.
"This is so weird. Then does a girl need to wait like a guy to make the vagina go back to normal".
"Yes, a girl has to wait to make her vagina go back to normal after the wave of sexual excitement hits her as well. A vagina will only increase its lubricant production meant for a seamless penetration of the penis when a woman gets sexually excited. But it won't show a bulge in pants like a penis."
Nina answered while controlling her chuckling. She understood Eren was trying to ask if there was a way to know if the girl is sexually excited for sure. Of course, there were some tell-tale signs. But she wouldn't tell Eren about them and make it easy for him to zero in on any girl that he'll come to know in the academy.
Plus, Eren might use those signs to identify her sexual state at the time, which was obviously in the 'active' state. She remembered seeing his erection last night, and though Eren had covered it by sitting with legs closed, she could see the erection he was currently having while this subject was being talked about.