Sayuri's math ability was actually quite strong. She started by throwing out a system of three linear equations for him to solve.
Wasn't this simple?
He learned in middle school.
Kaito naturally solved it easily.
Then Sayuri threw out a function problem, high school knowledge. Based on the title, given the hyperbolic original function y=shx, he didn't hesitate and quickly derived it.
Finally, Sayuri used her ultimate move, bringing out advanced mathematics learned in university, and it was continuous derivatives.
This was a bit difficult, after all, he wasn't a math major.
After some effort, Kaito finally derived the answer and looked at Sayuri with a victorious smile.
Now, she was at her wit's end!
Kaito countered with a difficult math problem. Sayuri was completely confused, then directly gave up and collapsed, not caring about anything anymore.
"Your linear algebra still needs work. You need to brush up on your knowledge of vector spaces."
Ridiculous. Wouldn't it be better to just sleep well?
Why run over to play math problems? It's asking for trouble!
"L-lost... Kaito, why is your math so strong?"
"Sigh, during my high school years, you don't know how many sets of 'Five Years of High School, Three Years of College Entrance Exams' we did. And I even started doing them from middle school."
Without practice books, he used the computer.
By searching for materials online, downloading them, and practicing, that's where Kaito started to grow.
And in university, his senior Xiao Yunyun even helped him out.
"Alright, let's sleep."
Tired, Kaito went to sleep. Sayuri also fell asleep smiling, holding him.
(T/N: For those who know, knows.)
…
Morning—
The sky was not cooperating. It was still raining heavily.
Although lighter than last night's downpour, it was still heavy rain.
Looking at the beach from an opening in the fence, the seawater had covered a large area of the beach, but it probably wouldn't reach here.
"Alright, get up."
"Hmm... I want to sleep a little more..."
Sayuri was very tired. Kaito wanted to indulge her, but he still pulled her up, walked to the storage area, took some water, and simply washed up.
After lighting the campfire, Kaito waited here. Sayuri hugged her knees, dozing off while warming herself.
It was simply that last night, Kaito's performance far exceeded her expectations, which was why she was so sleepy now.
Of course, Kaito thinking about math problems was also very handsome. At least she enjoyed watching.
"Oh? You're both awake?"
The first to wake up, as expected, was Kie.
She walked out of the rock house, couldn't help rubbing her hands together from the cold, but when she saw Kaito and Sayuri already warming themselves by the campfire, she also came over to greet them.
"Mrs. Kamado, good morning."
"Hehe, Kaito-san, as always, you're up very early. Mrs. Sawamura, I didn't expect you to be even earlier than me."
"She originally came out to use the bathroom, but when she saw me light this campfire, she simply continued her little nap here."
"Is that so? Indeed, the campfire is very warm. The fire in the room's fireplace is almost out."
Kie didn't suspect anything. Looking at Sayuri, whose face was rosy and seemed even more beautiful than before, she didn't think much of it, simply attributing it to the temperature of the campfire.
After all, when people are near the high temperature of a flame, their exposed skin becomes flushed.
"Oh right, Mrs. Kamado, let's try to make some warm food this morning. Soup would be better."
"Okay, I'll do that."
Kie nodded, then went to wash up, and took out some ingredients from the storage area to prepare soup.
Kaito also proactively helped, adding wood to the stove.
Gradually, everyone woke up.
Then some joined Sayuri by the campfire to warm up, while others came to help with cooking.
Among them, the usually lazy Ako also came to help, which was rare.
In the following time, everyone spent it in the heavy rain.
A whole day!
It didn't stop until evening.
During this time, Kaito had to use his ability to make a few decks of cards or other things for entertainment.
Because the environment was good, and food and wood were plentiful, no one had to go out in the rain. After the rain stopped in the evening, they did go out to cut some wood, throw it by the campfire to dry, and maybe use it as firewood later. This was just a precaution.
At night, perhaps because they had cards to play, everyone played a bit later. Kaito wasn't disturbed. That day passed like that.
The next morning, the tide had receded. The temperature after the rain gradually rose, becoming increasingly hot.
In the morning, everyone took the opportunity to go hunting. After raiding a few chicken and rabbit nests and finding some familiar vegetables, they returned with an abundant harvest.
In the afternoon, they continued swimming lessons.
This time, the student changed from Sayuri to Shodai.
Undoubtedly, like Sayuri, she loved taking advantage. After learning simple freestyle, she went back to rest. Next, Kaito started teaching Tearju.
"Tearju, relax, relax..."
"Hmm... s-sorry... I just can't seem to learn QAQ"
'Yes, with your balance this poor, how could you learn?'
Kaito looked at the white floating objects on Tearju, and a bead of sweat trickled down his forehead.
'Difficult, difficult.'
'No wonder Sephie stopped teaching her and left her to me!'
"Ahem, you don't necessarily have to learn freestyle. How about I teach you butterfly or breaststroke?"
Freestyle was hopeless. No matter what, it was very difficult.
So Kaito changed his approach and had her learn to swim underwater.
First, she could already float simply, thanks to her big assets.
After that, to guide her on how to do butterfly and breaststroke, Kaito expended a lot of effort. During the process, she hugged him countless times.
"┭┮﹏┭┮, I'm sorry... Kaito, I'm really too clumsy."
"Hahaha... it's okay, it's okay. Now you at least have the rudiments. I believe with two more days of practice, you'll learn!"
Kaito's face flushed, holding back a breath and smiling in response. Tearju, unaware of what was happening, kept hugging him.
Because she was too tired, having consumed too much energy.
"Ha..."
Sighing deeply, Kaito first brought her back to shore, then, without looking back, continued diving into the sea to calm down and catch some fish.
"Kaito, you're back! Wow, you caught so many fish?"
Shodai was resting by the beach. Seeing Kaito return, she immediately rushed over to help.
"Not bad. We're almost done with the fishing task."
Kaito smiled and put the fish into the rock tank for storage. He would leave them to be processed later.
"Uh-huh! Speaking of which, Kaito, because Eve couldn't sleep yesterday, we didn't come. Tonight, I'll come to your place!"