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Part 4
Kujou slowly stood up and took a beautiful box from the desk, on which books, documents, and so on were placed with one hand and handed it to Yumiko.
“What’s this? It looks like a wooden box.”
It was a wooden box that could be covered by two hands. Upon close examination, each side  was decorated with detailed geometric patterns.
“It’s called the secret box1. It is one of the traditional crafts in Japan that was composed of the technique of marquetry. Since it is called a secret box, it requires some techniques to open it. Oh, there is something wonderful placed inside, so please open it.”
While speaking, Kujou took out his phone from his pocket and began a call.
It was probably her first time seeing a secret box. She curiously turned the wooden box around and around, trying to find the opening.
“What happened, Kujou~ The cakes are ready to serve right now. Why are you calling me at this moment. Ah! What!? As I thought, you want to eat the cake too, right!?”
A happy voice leaked out from Kujou’s phone. This voice caused Kujou to pull a long face.
“Shut up, kid. I don’t need cakes. How is Miss Yui?”
“Um? She’s having a piece of chiffon cake with blueberry sauce intently right in front of me.”
“Oh, then it’s fine. Kid, you have work to do. Get out of the store and start an investigation right now.”
“What!? Are you an idiot!? I just said it’s the time that the cakes are ready to be served! I haven’t had a single bite yet!!”
Akira was intensely countering Kujou, who wanted to ruin the date. However, Kujou was always calm.
“By the way, that day is coming.”
“Wh, why are you suddenly saying that!? That day?”
“A few days ago, Miss Yui said she wanted me to teach her how to make chocolate… Chocolate… Speaking of making chocolate during winter2, maybe even an idiot like you can get what it meant.”
“Wait!? Eh!? That, is that!!…Va, Va, Va, Valenti…”
The sound of swallowing was able to be heard from the other side of the speaker.
“But. I don’t know who she’s giving the chocolate to. Kid, are you okay with that?.”
Kujou’s laughter leaked out.
“Are… You… Kidding me…”
Someone besides him.
Thinking about this possibility. Akira became speechless.
“Do you mind? I’m asking you to investigate for the client. Isn’t it nice to show Miss Yui that you are capable? I’m giving you a cha~nce!”
“I’ll do it!!”
It was an immediate reply.
“I see! That’s great. Then show Miss Yui your capabilities.”
“Yeah!!”
Kujou’s mouth distorted to the shape of a bow even more. He showed a guts pose3 with the smile of a devil.
Sadly, Akira did not have any chance to know it.
“Are you still in Hatsudai4?”
“Yeah. I was talking to Yui about it before, and then we decided to eat around all of Hatsudai today.”
“I see. That’s nice. Then start inquiring if there are witnesses of betobeto-san, suspicious people, or something like that immediately.”
“Eh?… I get suspicious people, but betobeto-san… Are you talking about the betobeto-san that appears at the night?”
“Right.”
“Well. I can ask about suspicious people normally… But youkai… How am I supposed to do that?”
Akira’s powerless voice with apparent worries was transmitted to Kujou through the speaker.
“As you know, betobeto-san is a kind of youkai that chase after people at night. There is a high possibility of it sauntering on the streets. People who live there or pass there for work or school may witness it. Just go ask them for now”
“‘Just go ask…’ Well, that’s the only thing I can do… Okay!! I got it.  I well try!!”
“Um. I’m counting on you. And ask police about the suspicious people. We should be able to get correct information from them.”
“Got it~”
The conversation ended there.
Immediately after that.
There were a sound of a hard object falling onto the ground. Kujou turned his head to Yumiko.
“You don’t believe me at all!! It’s enough to inquire about betobeto-san only!”
Yumiko was suddenly infuriated, but Kujou acted like nothing had happened, gently sitting onto the sofa and finishing the black tea.
Yumiko stared at Kujou with heavy breathing.
However, Kujou just ignored her.
“… The secret box. Oh？Have you opened it?”
Still indignant, Yumiko looked at the wood box that was thrown onto the floor.
“What is this!? What do you mean by ‘Open it!’ There isn’t a single opening or a keyhole! It is just a cuboid box. How am I supposed to open it!! Are you making fun of me!!”
Kujou gently picked up the box, which was thrown by Yumiko, that was rolling on the ground desolately.
“Many phenomena in this world are caused by multiple factors. If you only focus on what you see, you may lose the basics of matters. ”
Saying that, Kujou put his fingers on the four sides of the wooden box and started to solve it slowly.
Eventually, he found something strange.
“I see. It’s right here.”
Kujou used his fingers to push a small part of a side horizontally.
Thereupon, part of the beautifully arranged geometric patterns slightly moved to the right.
Yumiko’s eyes popped out.
“… What… Happened?”
“I said it at first, that some techniques are required in order to open this wooden box. As you see, this is simply a puzzle box.”
Smiling, Kujou handed the wooden box with its first lock opened to Yumiko.
Her eyes, which were still filled with anger, were focused on the box.
“This box is arranged in a way that several locks are required to be unlocked before you can get to the innermost part. The first lock that you said was impossible to open was now opened. The second one. Please try it.”
Unable to reject, Yumiko moved her hands slightly.
She tried to push the upper part to the right, the large sides to the right, and the opposite small sides to the right just as what Kujou had done.
However, the wooden box continued keeping the secret stubbornly.
Holding the immobile box, Yumiko’s hands gradually began to shiver, and her breath became rough.
“What is this… I can’t do it! Impossible!!”
While speaking, she knocked the table with the wooden box this time.
Kujou breathed out lightly, gently looked at her trembling due to the anger, and softly picked up the box, which was thrown away again.
“Unable to complete what you are doing for the first time is natrual. Hitting the wall is also natural. But things will change according to what you think and what you decide to do.”
When Kujou took the box, his observed the right part that he had moved before. Same as before, he put his fingers on the four sides.
Probably because he had found something strange, he pushed hard with his fingers under the right part he had moved before.
The geometric patterns moved to the left this time.
“Although they had been moved to the right once, it didn’t mean they can not be moved to the right.”
Although Yumiko’s breath was still rough, she was slightly attracted by the brilliant movement of Kujou’s hand.
She fixed her breathing and received the box from Kujou. She pushed the side on which the third lock was supposed to be, and then the upper and lower part to the right and to the left respectively.
Kujou smiled while watching her.
When the warm Nilgiri tea was completely cooled down, a call from Akira caused the vibration in Kujou’s inside pocket.
“Hello, Kujou? This is me.”
“Which ‘Me?’ It sounds like a call from a fraud. Do it again. ”
While saying so, Kujou slowly ended the call.
Right after that.
As if it was expressing the feeling of the caller, the phone vibrated intensively.
Kujou accepted the call thinking, “Oh, well.”
“So Akira. You are calling me so early. What about the inquiry? ”
“Didn’t you know it was me!!”
Akira shouted his anger out from over the speaker.
“Just so you know, I’m telling you that I’m not inquiring for your sake! I wanted to show Yui that I am a man who is capable of working so desperately. That’s why I’m working hard!! I ran over and over to ask people.”
“Then keep asking until you become barefoot. So what is the result of the inquiry? If you can’t even give me a satisfying report, you are not qualified for the case of the chocolate..”
“Ah… Damn it…”
Recalling the case regarding chocolate, Akira started to talk about the results of the investigation obediently.
“I went into stores starting from the very beginning on the street and inquired, but there weren’t any witnesses regarding betobeto-san. Then I asked the people walking on the streets and kids playing in the park; however, they said they knew nothing about that kind of youkai.”
“What about the suspicious people?”
“U~m, I asked about that as well, but no results. Although I went to the police station near the New National Theatre, the police said they heard nothing about anyone seeing suspicious people in one month. Oh, but they said there was a missing person.”
“… Hum? The police said that?”
“Right. The police at the police station near the theatre said that.”
Kujou closed his eyes as if he was thinking about something, but then quickly opened them again.
“I see. So where are you right now?”
“Near the New National Theatre. Yui said she wanted to buy the famous cookie sandwich that people always line up for at the store. We are on the way to the store.”
“Then besides the case about betobeto-san, also inquire about makurakaeshi, hidarugami, and azukiarai while you go there.”
“What!? Isn’t that too much? Or you want me to ask about other youkai because there is no evidence on betobeto-san’s existence?”
“Complaints are not accepted. Shut up and show Miss Yui your capabilities.”
“O, oh.”
Hearing Akira’s reply, Kujou put his phone into his pocket.
“Where are they right now?”
Unable to open the third lock, Yumiko asked without moving her eyes away from the secret box.
“It seems like they want to buy a cookie sandwich which is so popular that people always line up for, so they are moving forward to the shop.”
“Sucre Ciel in Hatsudai!! That’s my favorite store!! Its Custard and Fresh Cream Cookie Sandwich is really delicious!! To the extent that I want to eat it every day!!”
She must be very fond of the cookie sandwiches. All the attention she put onto the box was interceded by this conversation.
“Really? Then I will ask him to buy one for you if he calls me again.”
“Ah, no, I didn’t mean that…”
Slightly embarrassed, Yumiko started to find the lock of the box like she had been doing at the beginning.
“It’s fine. Anyways, the one who is going to buy it is the kid who does all the odd jobs, so there is no need to be concerned about him. By the way, how was the box? Are you able to solve the third lock?”
Saying that, Kujou took out the phone that he had put away earlier, launched Messages and sent a message.
“U~m,” after being troubled for a while, she opened her mouth with her eyes on the box.
“I tried what you had done to use fingers to search on the sides, then I found a weird, thin protrusion. I tried every mean, but it wouldn’t move. It has nothing to do with force, right?”
“No. It has nothing to do with force.”
She, who had thrown a tantrum about the box, started to have a conversation about the box.
Kujou was satisfied and stretched out his hand gently.
“Both right and left did not work. Then how about this: try to broaden your horizons this time.”
“Horizons?”
The response vague, her eyes and fingers were searching and moving around the box frantically.
The next second, a thrill sound of a piece of metal disrupted her attention from the box.
This sudden accident attracted Yumiko’s attention to Kujou.
“Oh. I apologize. How can I make a mistake like dropping a spoon onto the ground?”
As she looked down, she saw a teaspoon shaking slightly on the ground.
“Excuse me. Can you pretend the side with irregular protrusions on its left and right sides to be the front?”
She turned the box around as she was told by Kujou in order to find that side.
“But this side was already moved, so I don’t think there will be anything.”
“Right, if you only look at the point and the line. So this time, let’s focus on things on a surface. Please think about surfaces instead of parts.”
Yumiko though for a while after Kujou’s reply, she put force onto the whole surfaces of the small sides. Next, she turned to the top, put force onto both the left and the right, and the bottom at last.
“Click!” With a pleasant sound, the small sides moved downwards as a whole.
“Yes–!!”
Kujou smiled silently at Yumiko, whose face beamed with a smile for the first time after she came to this house.
“Until now, you were focusing on sides such as a part of a large side, a part of a small side, instead of the surface. It is great to focus on a certain part; however, when you are stuck, it is important to relax. Oh, I realized that I forgot to tell you… It was the case regarding betobeto-san, that nothing could prove its existence on the streets according to Akira’s inquiry.”
“Oh… I see… ”
Her expression was slightly clouded.
“However, since I’ve asked him to inquire about other youkai as well after that, please wait here for a while. Plus, the locks of the secret box are almost opened, please continue.”
As if she was answering Kujou’s encouragement, Yumiko nodded earnestly.
Immediately after that, there was a call coming from Akira.
“Ah, is that Kujou? This is me… Akira.”
“Hum. You seem to have the ability to learn. Then? Isn’t is too fast for you to inquire?”
“No!! Yui became sulky!”
“What!?”
Kujou, whose face was calm until now, transformed into the look of Bishamonten5.
“You little kid! What had you done to Miss Yui! Did she meet a suspicious person, was sexually harassed, or kidnapped!? Or don’t tell me that she was punched!! You devil, you beast, I won’t forgive you!! Tell me your location. I’m going to get you immediately!!”
The image of Kujou yelling and gashing his lip in wrath without wiping the blood appeared in Akira’s head, so he explained immediately.
“Wait! You misunderstood! How could I do that!! Calm down!… When we were walking towards to the cookie sandwich shop, I inquired in between for a few times. So when we arrived, there was a super long line waiting in front of the store… We hurried and lined up. Then there was an old woman standing before us. Since she said, ‘I brought a smartphone for the first time, but I do not know how to use it except for the camera,’ so I helped her extremely~ courteously… But then… But then! That woman said, ‘Give me all the cookie sandwich,’ and she bought like ten of them!! So they were sold out, sold out!! Then Yui said, ‘If Akira wasn’t inquiring, then we were able to buy it!’ She became angry and sulky…  ”
“Oh. Then good luck.”
Saying that, Kujou ended the call one-sidedly.
Soon, the phone vibrated as always.
Clicking his tongue, Kujou decided to answer the call.
“How could you end the call that arbitrarily! In the first place, it was your fault causing her to become sulky!!”
Kujou sighed once at Akira, who kept talking on and on.
“Listen to me, Akira. Men who can work while caring for women are considered capable, which means that they will be sought after. In the first place, the madam asking for all the cookie sandwiches marked your failure. I can’t do anything with it. However, if you can calm down the depressed heart of a lady, you points will probably increase even more.”
“So you want me to comfort her?”
“Admit your fault, and take her to the next store casually.”
“No. I don’t even know that kind of stores.”
“There should be an elementary school near you. Right beside it, there is a dessert store which sells fruit galette. At there, even Miss Yui will return to a good mood.”
“Really!? Thank you, Kujou!!”
“Umm, listen to me. Admit your fault first.”
“Yeah! It’s easy!!”
“Ah~ Oh, Akira. Don’t forget about what I’ve talked about in the message.”
“No problem no problem! I asked the old woman and some couples at the shore when we were lining up. I will text you later.”
“Okay. I’m counting on you. Ah, I’ll send you another message later. Execute it.”
Akira’s voice became more cheerful since he had received the method to comfort Yui from Kujou.
However, Kujou’s mouth distorted to the shape of a bow even more.
Akira wasn’t aware of it.
The true intention of the strategy Kujou bestowed on him.
He wanted Akira to admit that it wasn’t anyone’s order but his own mistake that made Yui unpleasant.
Laughter leaked out from Kujou’s mouth as he was satisfied with his method of inducing Akira to admit his fault.
Yumiko watched this butler laughing out loud while texting in wonder.