I sat in Rina's Restaurant, looking over the flash cards I prepared during the weekend. Kondou was sitting next to me, looking bored out of her mind, as she had already finished her sweets and drink. I felt bad for her, because I was the one who dragged her out of her apartment so she could tutor Shimada.
Shimada's... really late though. We said to meet at 4pm, but it's now been nearly half an hour. Waiting around for him made Kondou irritated, as she had nothing else to do. Though, some sunlight would do her good. Her skin's pale, like a vampire. Guess I can't judge, since Yumi also says I need to go out more...
In the first place, it was Yumi's idea to get Kondou to tutor him. She arranged a meeting for them and everything, but since she had an emergency today, I got forced to be her stand-in. Being the older twin sucks sometimes. Besides, it's Shimada's responsibility to learn the material. At the rate he's doing, he's going to drop out of A Class.
Though, it could be a good thing... shedding off the dead weight.
"Hey, sorry I'm late."
Shimada strolled over to our booth nonchalantly. Plopping down his messenger bag, he threw out three exams on our table. One mock exam for biology, chemistry and physics he received from Ike-sensei, so we can gauge how he is in these areas.
His biology score was 7/100. His chemistry score was 6/100. His physics score was 4/100.
What an appalling attempt. It was embarrassing he was in A Class. I'm sure even an E Class student could score higher if they tried. There was nothing Shimada had going for him. While everyone was excelling, he always lagged behind.
He doesn't even wear the uniform properly. He uses a black shirt and doesn't put on his tie. It's disgraceful.
"I really tried too." Shimada said in his characteristic tired voice. Did he really care this little about his score?
I wish he got sent to E Class. That's where he belongs. In the dumps with the rest of them. Kondou exhaled loudly as she stared at the scores.
"Tell your sister I'm going to kill her."
I sympathised with Kondou's frustrations. Yumi was too hopeful in other people, including Shimada. There was no way he'd turn things around in two weeks. It was better to let him sink to a lower class.
"Itsuki, don't give up faith so easily. C'mon, just tell me the answers to this test."
Shimada pushed the physics paper in front of her.
"Refrain from using my first name. I haven't given you permission."
Kondou sharply snapped back at the carefree Shimada.
"But Yami, Shuu and Hane all let me call them by their first names."
"Well, that's them. I am different."
"I don't see the difference. We're all in A Class. We might as well be friendly with each other."
Shimada had a conceited grin the entire time he talked to Kondou.
"Oh, please just shut up! You're going to drop out to E Class anyways, so what's the point in tutoring someone as stupid as you?!"
Kondou slammed her books on the table and stood up.
"Thanks for wasting my time, Yamamoto-san!"
Everyone in the restaurant turned our way hearing Kondou get so agitated over Shimada.
"And I hope you get expelled, Shimada!"
Kondou left in a fit of rage and embarrassment.
Shimada looked over his shoulder and laughed, kicking up his feet onto the table.
"Sure is nice without her whiny voice around. Yami, I guess the job of tutoring me falls to you."
I have no other choice. Even if he's lazy and obstinate, Shimada's someone who I don't want to mess with.
"Sure. Let's start off with electricity and circuits. On the exam, one of the questions was to label the symbols."
I took his exam and flipped it open to the first question. Spreading it out on the table, I tried to get his attention, but he was on his phone, not looking at me.
"Huh? Symbols? Okay."
Shimada looked away from his phone and glanced at the symbols briefly.
"The two at the top are switches. They're used to turn a circuit on or off. To turn the circuit on, you close the switch, to turn it off, you open it."
I flinched. He gave a perfect answer to part B of this question, yet he got no marks on this question. He wrote down the entirely wrong component on the symbols.
"Okay... uh, how about this one?" I pointed at the lamp.
"It's a lightbulb. A current heats the filament inside it, so it gives out light."
I was confounded again. He got this wrong the first time, though. Annoyingly, Shimada went back to scrolling through his phone.
"Okay, this one?" I pointed at the resistor.
"A resistor, huh? It restricts or limits the flow of a current. A fixed resistor has a resistance that doesn't change."
I leaned over the table and snatched the phone out of his hands.
"Stop cheating."
"Huh? I was just reading the group chat messages. Everyone sure is busy revising. Seems unnecessary, and boring."
I looked at the contents displayed on the screen. It was indeed the lively group chat. I narrowed my eyes and grudgingly gave it back.
"Do you seriously doubt my abilities?"
Shimada put down his feet and leaned forward, with a smirk. He placed his phone on the table face down, and his conceited smile returned.
"But... if you know it, you shouldn't have gotten a bad score, wouldn't you?"
Shimada shrugged and laughed under his breath.
"I don't give a shit about test scores. The only time what's in my head matters is when I have to win. Going over this stuff is a piece of cake for me."
You can't win without the necessary tools and thoroughly preparing. His nonchalant personality is going to bite him back one day.
"But how about you, Yami? Isn't it difficult?"
There was clear venom in his voice. He was mocking me. To be honest, I was a little scared.
I didn't want to anger him, since he was so unpredictable. Shimada's always effortlessly warped the air.
"I'm not an academic person. I can see a solution through problem-solving."
"Which is why maths is your strongest subject. Let's flip this dull study session on it's head. Today, I'll tutor you."
Shimada snatched up his test paper, scrunched it up, and let it fall into my lap.
I looked at the screwed up ball, and picked it up. What was even going on inside that guy's head...
"Now, let's see if you can keep up with my teaching. I'm going to be relentless. Though, you're in A Class, so you can keep up."
Why was he trying to make an enemy out of me?
"Oi, Shinpei! Get me a bottle of cola! I'm dying over here!"
Shimada stood up on his seat and shouted across the restaurant. Keisaki nodded in response, going to the kitchen to get his drink. A few minutes later, he placed it on Shimada's table.
"Alright, Yami. Let's begin your hellish revision session."
Concentrate and focus. I'll seize a moment where he goes wrong and correct him to establish superiority in our relationship. I can't let him act so carefree anymore.
"A variable resistor is a resistor that can be adjusted to change the resistance. It's used in dimmer switches and volume controls."
Correct...
"A thermistor is a resistor that changes resistance depending on the temperature. If it's low, it has a high resistance. If it's high, it has low resistance. It can be used in thermostats or heat activated fire alarms."
Also correct...
"A light-dependent resistor, or LDR, is a resistor that changes resistance depending on light intensity. Low light levels have high resistance, high light levels have low resistance. It can be used as a sensor in cameras or automatic lights."
Correct again...
"A semiconductor diode allows current to flow in one direction only. Current will not flow in the other direction. Diodes are used to convert an alternating current into a direct current."
Shimada took a swig of his cola.
"Got all that?"
The way he rapid fired those answers without missing a beat or blinking scared me. He recalled everything perfectly, and I could barely keep up.
Just be patient, Yami... you'll find your moment where he trips up. No way he can be this good. It's a bluff.
"Anyways, that's just the first page. Now, I'm gonna speed up."
Shimada slammed the bottle down, wiping the back of his mouth. There was no way he could go faster.
"There're two types of current: directing and alternating. In a direct current, the flow of electrons is consistently in one direction around the circuit. In an alternating current, the direction of electron flow continually reverses."
In other words, a direct current goes one way, while an alternating current reverses direction.
"Electrons are negatively charged particles that transfer energy through wires as electricity. Charge is a property of a body which experiences a force in electric field. It's measured in coulombs (C). One coulomb of charge is equivalent to 6,250,000,000,000,000,000 electrons."
Wait. The way he recalled that huge number... could it be?
"In a closed circuit that includes a source of potential difference, or voltage, there'll be a current flowing around the circuit. Electrical current in a metal is a flow of electrons. When current flows, electrical work is done and energy is transferred. The amount of charge passing a point in the circuit can be calculated using this equation."
Shimada picked up a pen and scribbled on the papers laying on the table, "Charge = Current x Time/Q = I x t."
"Q is measured in coulombs. I is measured in amperes, or amps. T is measured in seconds. One amp is the current that flows when one coulomb of charge passes a point in a circuit in one second. For example, a current of 1.5A flows through a simple circuit. How many coulombs of charge flow through a point in 60 seconds?"
Shimada took another swig of cola.
"C'mon, Yami. Math's your strong suit. Calculate it."
"60 x 1.5 is 90."
"That's right. How about when it's 13A and 10 seconds?"
"130 coulombs."
"Hey, you're getting the hang of it."
I hate that he's looking down on me, but I know that I'm just as strong in these subjects. I can't be thrown off by his sudden intelligence, because I think I figured out the trick behind Shimada's knowledge.
"You measure current with an ammeter. To measure the current through a component, the ammeter must be placed in series with that component. Series, by the way, is a circuit where one component follows directly from another. Example, three bulbs in a row is connected in series."
Shimada Kuroshi isn't a smart person. He's ingenious for all the wrong reasons.
"The current through a component depends on both the resistance of the component and the potential difference across the component. Commit this much to your lacking brain: potential difference is a measure of how much energy is transferred between two points in a circuit."
Shimada's "trick" is eidetic memory.
That's why he's in A Class. He can remember anything he needs or wants. Then, he can apply what he's photographed in his mind into the exams, without ever wasting energy studying.
"To measure potential difference across a component, you have to place a voltmeter in parallel with that component. That way, you can measure the difference in energy from one side to the other. Potential difference is also known as voltage, to no one's surprise. It's measured in volts (V)."
That's why he's ingenious. He uses his own strengths to their fullest advantages. If he could actually be bothered to answer the exams, he could easily score full marks.
"When a charge moves through a potential difference, electrical work is done and energy transferred. The energy transferred can be calculated using another equation."
Shimada scribbled on the paper, "Energy transferred = Charge moved x Potential difference/E = Q x V."
"Potential difference is measured in volts (V), energy is measured in joules (J), charge is measured in coulombs (C). One volt is the potential difference when one coulomb of charge transfers one joule of energy. You can rearrange it to find voltage."
When you rearrange it, you get V = E/Q.
"Try this one. How much energy is transferred when 3 coulombs move through a voltage of 6?"
"If E = V x Q... then 6 x 3 is 18?"
"You're correct. Try not to sound so anxious next time."
Shimada grinned, finishing the cola bottle.
"Shit, I ran out. Oi, Shinpei, get me another bottle!"
I knew Shimada was abrasive, but to be this rough in public too... I felt embarrassed to be sitting at the same booth as him.
Keisaki handed Shimada another ice cold bottle of cola. He looked unhappy to have to serve him again.
"That's the only thing that guy's useful for."
Shimada popped the bottle open and drank some more cola. If there's one thing I've noticed, it's that he has an unhealthy obsession with sugar.
"Resistance is the measure of the difficulty of passing an electric current through a conductor. The higher the resistance, the harder it is for the current to flow. Electrons in the current bump into the positive metal ions as they travel through the wire. Resistance increases if the wire gets longer or thinner. If the wire is longer, there're more ions to bump into. A thin wire has a smaller cross sectional area, which means there are fewer electrons to carry the current."
Shimada finished his swift explanation and wrote another equation on the paper, "Resistance = Potential difference ÷ Current/R = V / I."
"Resistance is measured in Ohms, potential difference is measured in volts (V), current is measured in amps (A). If you've noticed, this is another way to calculate the voltage, if you rearrange the equation."
"V = I x R."
"Heh, yeah. This equation shows that increasing the resistance for potential difference reduces the current. An example is using a variable resistor. Adjusting it to double its initial resistance will halve the passing current."
Before Shimada could continue, I decided to cut in. I couldn't handle anymore of him for today. He was getting on my nerves with his nonchalant behaviour and arrogant smirk.
"You were going to say next: conductors have low resistance, while insulators have large resistances."
Shimada narrowed his brows and laughed, drinking some more cola. Wiping his mouth with the back of his sleeve, he nodded, slamming the bottle on the table.
"You're not wrong. However..."
Shimada's foot thrusted into the middle of my shin. I flinched, and pulled my leg back. He looked down on me with a condescending smile.
"Who said you could interrupt?"
I clicked my tongue, grabbed my stuff and stood up. Even though I've experienced many hits on my legs, it usually goes away due to my high pain tolerance. However, Shimada's blow continued to throb painfully.
"I'm done for today... thanks for the revision session, Shimada." I said through gritted teeth.
I staggered past him, before nearly tripping over. My reflex arc kicked in, keeping me up, barely.
I looked over my shoulder and saw Shimada's foot sticking out where I was walking.
"Whoops. You should look where you're goin', Yami. Stop daydreaming."
Shimada taunted me with his conceited smirk. I wanted to wipe it off his face, but there were two problems.
The first, I'm not a physical person. I'm more skilled if we're playing Vanguard. The second, I don't want to make an enemy out of him. Despite my irritation for him, even I know that he's not normal.
Shimada is a dangerous person and the blight of A Class.
We only have to endure his abuse for a little longer. There's no way he'd be able to stay in A Class after all he's done.
Just a little longer... before we can look down on him and laugh at his stupid face.
I left the restaurant and hissed in pain.