Walking into the tunnel platform, Robin immediately felt an indescribable stuffiness, he subconsciously loosened his collar and asked, "You usually rely on this for travel?" ”

Booker had asked the same question to his predecessors when he first came to Mercury, so he smiled and said, "Sir, this is Mercury." Mercury is only one-third larger than the Moon, and because it is the closest planet to the Sun, Mercury's surface temperature is more than 400 degrees. In addition, Mercury is almost a metal planet, so it is impossible to build a 'vacuum chamber' here. There are only a few tunnels like this in Mercury, and they are not connected to each other. ”

After saying that, Booker took out an old-fashioned infantry helmet from his bag, handed it to Robin, and said, "Sir, you can use my helmet, I have a spare one." ”

"No, I have a filter mask." Robin took out a new type of filter mask and immediately felt a little easier to breathe when he put it on.

Throwing their bags into the car, Robin and Booker took the front seats. The miners also got on board after packing their bags, and soon filled the large transport truck that could accommodate hundreds of people.

After a whistle sounded on the platform, the old-fashioned transporter slowly started and drove into the dark and deep underground tunnel.

The underground tunnel where the transporter travels is unlit, so Robin and the others spend most of the way in the dark, and there are occasional drops or two of hot metal slurry dripping from the top of the tunnel, which makes Robin uncomfortable at first, but the others seem to have become accustomed to it, and they don't care about the metal slurry that crackles the roof of the transporter.

"It's like that, sometimes a stream of lava suddenly falls from the tunnel, and in that case, the lines of communication have to be closed and you have to wait until they're cleared before you can use them." Booker smiled embarrassedly at Robin, and suddenly asked cautiously, "Sir, may I ask a question?" ”

"Just ask."

"Why are you here?"

"Because my father is here."

"He's ......"

"He came here to work on his own volition." Robin sighed and added, "To feed my ......"

“……”

Perhaps sensing that Robin's mood was a little low, Booker was very interested in not continuing the topic.

Shortly thereafter, after changing to Line 7, Booker took Robin to a humble rest stop.

The rest stop is located on the ridge of a circumferential mountain, with a view of the bottomless cliffs and the dazzling sunlight above you.

After looking at the time, Booker gave a few words to the other miners who were waiting here, and then said to Robin, "Sir, wait ten minutes for the sun to go down, and we will take the cable car to the steel grotto." Sir, what steel cave did your father work in? ”

"Number 5."

"Five?" Hearing the number of the steel cave where Robin's father was, Booker showed a look of surprise: "Then your father must have been here for a long time." ”

"Yes, it's been eight years."

"Eight years? It's admirable. You have a good father. ”

Robin smiled bitterly, "Yes, I think so too." ”

After a few moments in the rest stop, the scorching heat outside began to dissipate, and the dazzling almost white sunlight began to slowly turn yellow.

Booker looked at the outdoor temperature detector hanging in the rest stop, and after seeing the detector's red indicator turn green, he took out two sets of heat protective suits from the open storage cabinet of the rest station and put them on with Robin.

This high-temperature protective suit, which resembles an old spacesuit, is better than light infantry armor in terms of heat insulation. After putting on the protective suits, Booker and Robin, who are slightly bloated, get into a vertical cable car that slowly rises from the bottom of the crater.

As the cable car descends rapidly, the steep charred cliffs around the crater suddenly appear in front of Robin's eyes, and he even sees several waterfall-like lava streams splashing down the inner slope of the crater, which is like the hell depicted in the Divine Comedy.

"I can't imagine that humans could live in such a place."

"Mercury contains a large amount of metallic materials, including many rare metals. Hundreds of millions of tons of metal are transported from here every week, so Mercury supports almost the entire republic's steel needs. Booker smiled proudly at Robin, "This is also an indispensable place for the Republic. ”

"Huh?" At this time, Robin suddenly noticed that the temperature around him began to drop sharply, from more than 300 degrees Celsius to more than minus 50 degrees, and it was still dropping rapidly.

"Why did the temperature drop so low all of a sudden?" Robin asked curiously.

"This is the North Pole of Mercury, and because of Mercury's special orbit, the Sun is always hovering on the horizon in the North Pole. Due to the lack of direct sunlight, the temperature inside the crater is low because it never sees sunlight, and the temperature in the deepest part of the crater is only minus 161 degrees, and there is even a small amount of ice stored. Speaking of which, Booker explains: "Your father's No. 5 steel cave is one of the deepest steel caves. ”

As he spoke, the cable car had already taken Robin and Booker into the area where the steel cave was located. Robin looked around and saw that the steep cliff walls of the crater were densely covered with countless steel caves like honeycombs. The spectacle made Robin speechless for a long time.

"My father...... Do you live in a place like this......"

Looking at the figures swaying from time to time in the steel caves around him, Robin suddenly felt an indescribable complex emotion welling up in his heart. There seems to be the excitement of reuniting with his long-lost father, and there seems to be a kind of nervousness for no reason, which makes Robin inexplicably restless.

With this in mind, the old cable car made a 'whoosh' and stopped in front of a steel cave that looked very dilapidated.

Opening the cable car's insulated metal door, Booker leads Robin into a tunnel-like cavern, and after walking a short distance, Robin sees a rusty metal sealed door.

Pressing the communication device attached to the sealed door, a hoarse voice suddenly rang out from the communicator.

"Who? I don't have anything to eat, I'm going to eat something else. ”

“……”

Booker smiled wryly at Robin and explained into the communicator, "I'm Booker, I'm here with a chief......"

"It's Booker, you're in the wrong place. I don't know any sir. ”

With this sound, the metal-sealed door opened with a 'whoosh'. And when Robin saw the old figure standing behind the metal automatic door, he suddenly stood in place as if struck by lightning.

"Sir, you can take off your heat suit."

Booker walked through the door with Robin and took off his protective suit, but when he looked back, he found Robin motionless as if he was stunned, so he carefully called, "Sir? ”

“……”

Robin shuddered and took off the round helmet of the protective suit, looking at the wrinkled old face behind the automatic door, and his eyes suddenly turned red.

"You ......"

Behind the automatic door, the old man with his back was obviously stunned after seeing Robin's face, and after carefully distinguishing it for a long time, he suddenly woke up: "Robin! ~You...... You're Robin! ～”

"Yes, Dad......" Seeing that his father recognized him, Robin wiped his red eyes hard, and choked up and smiled: "I came to see you......"

"Robin, you're really Robin! ~Damn, why are you here! ”

The joy of reunion after a long absence made Robin's father excitedly pull open the automatic door, looking at his son who had not seen him for eight years, and couldn't help but cry: "Come in, come in......"

Robin was dragged into the steel cave by his father, and Booker, who led the way for Robin, did not come in because he didn't want to disturb the reunion of Robin's father and son after a long absence.

Robin's father wanted Booker to stay for a meal, but Booker insisted on leaving on the grounds that supplies had not yet been distributed, so he saluted Robin and took the cable car out of Cave 5.

"Robin, why are you here all of a sudden...... I haven't seen each other in eight years, and all of a sudden I can't even recognize it when I grow so big......" Closing the sealed door, Robin's father was so excited that he didn't even know what to say.

"I have a long vacation, so I wanted to come and see you." Robin took off his bloated hazmat suit, revealing a black Air Force captain's uniform.

"Huh?" Robin's father saw the silver shamrock epaulettes on Robin's shoulders at a glance, and couldn't help but exclaim, "This ...... Is this the Captain? ”

"Yes." Seeing his father's surprised eyes, Robin's heart suddenly swelled with an unprecedented sense of great achievement, he proudly straightened his chest, and smiled a little shyly: "I just got promoted." ”

"No wonder that Booker kid said sir, it turns out that you are already a captain! ~" Robin's father patted Robin on the shoulder vigorously and sighed with relief: "It's worthy of my son, celebrate!" ~I've got to celebrate, hahaha......"

Pulling Robin into the room inside the steel grotto, Robin's father went to fetch some food, spread it out on the table and sat Robin down.

Looking at the simplest fast food on the table, he looked at Robin nervously: "This place is a little bitter, there is nothing to eat." We're going to ...... about it."

Robin knew what his father was worried about, picked up the spoon and scooped it into his mouth, and said vaguely: "These things are good, I don't eat as well in the army, and sometimes I can't even eat a meal for a few days." ”

"Yes......" Hearing Robin describe the hard life of the army, his father couldn't help but be a little worried, but seeing that Robin seemed to be eating well, he suddenly showed a happy smile, and scooped up some more food in his food box to Robin: "Then eat more, it's not enough for Dad to get it again." Here, Dad's words are still very effective, don't worry, hahaha......"

"Dad......" Hearing his father's words, Robin looked up at the wrinkles on his father's face when he smiled, and then looked at the old and simple metal furniture in the room, and couldn't help but put down the spoon with heavy eyes, and said seriously: "Dad, in fact, you don't have to stay here, you see, I have grown up." I am now an officer and I can support myself. And you should have accumulated a lot of contribution points in Mercury over the years, even if it is not much, I didn't do much to the ones you put into my account when I was studying, according to the regulations, as long as you pay a part of the handling fee, this part of the contribution points can be returned to you. So you can get a relaxing job in Wald and live a more comfortable life. Dad, if you agree, I'll help you submit your resignation application tomorrow, how about it? ”

(To be continued)