"What do you mean, 'merged into one'?!" Isis's voice rose despite herself.
"I mean exactly what I said." The director still wore her enigmatic half-smile. "For example, modern research tells us that the ancestors of plants were originally incapable of photosynthesis. At some point, however, one of those ancestors swallowed a type of algae. Rather than digesting it, the two achieved endosymbiosis, eventually forming the chloroplasts that plants now use to synthesize nutrients from sunlight.
"Mr. Altaïr's situation is somewhat similar. We still cannot be sure what effects this endosymbiosis will have, but it should not be harmful. After all, to those microorganisms, his body has become their new home. Who would destroy their own home, right?"
"But... but isn't that..." Isis stammered before finally finding the words. "Wouldn't that be extremely dangerous? Can't we simply kill those microbes and remove them, solving the problem once and for all?"
"Theoretically, yes." The director gave a slight nod. "But that would involve some risk."
Isis pressed her at once. "What kind of risk?"
"The risk of death."
"..." The words died in Isis's throat.
"I am not trying to frighten you." The director's expression turned serious. "Take the Frenzy Virus outbreak, for example. Do you know the enormous price people paid to develop targeted medicines and treatments? At the time, vast numbers of people were infected and certain to die without treatment, so researchers had no choice but to test one aggressive approach after another until they finally found a relatively safe and effective treatment. It is impossible to tally how many people died during that process... Mr. Altaïr is indeed infected with microorganisms, but compared with the deadly spores of the Frenzy Virus, these microbes do not even pose an immediate threat to his life. We have not detected any effects at all. Do you truly think we should subject him to aggressive treatments and repeated trial and error under the present circumstances?"
"Absolutely not!" Isis shook her head rapidly.
She finally understood what Alva had meant when he said, "The human body is amazing, and most problems can be resolved through self-healing." There was no sense trying to fix what was not broken; reckless treatment might create a problem where none existed.
"So what should I do now?" asked Altaïr, who had been silent for some time.
"For now, we keep observing. Come back every three days from now on."
"Wasn't it once a week?"
"That was before. Now your body appears to be moving toward endosymbiosis with the microorganisms inside it, so we need to monitor you more closely."
"...All right." Altaïr had no choice but to agree.
He was not especially afraid or anxious, but claiming he felt no concern at all would have been a lie. Knowing that the microbes regarded his body as their new "home" also left him with a strange feeling.
On the way home, Isis remained visibly worried.
Things were moving in an unknown direction. Even Alva and the director, expert researchers who had helped combat the Frenzy Virus, could not predict how the microorganisms inside Altaïr might develop in the future.
What were they supposed to do...?
"It's all Dad's fault!" Isis suddenly kicked a roadside stone step and said resentfully, "When the coin toss told us to go north, he had to get some ridiculous idea in his head and take us south. None of this would have happened otherwise.
"I'm going to write him a letter and give him a piece of my mind!"
It took Altaïr two seconds to realize what she meant. Mr. Gordon was entirely innocent in all this; Isis was simply taking her frustration out on him.
Altaïr spent much of the walk talking Isis down. By the time they reached home, she had finally calmed somewhat. Standing outside the front door, however, she remembered what they had discussed there earlier.
"Given your condition, why don't you speak to the Guild Manager? That Arena Challenge... maybe you should sit it out after all."
Altaïr sighed. "What condition? Didn't the director just say it was a good sign, not a bad one, that the microbes inside me were moving toward endosymbiosis?
"They gave me a thorough physical examination, too, and found no effects at all. In fact, I can faintly feel myself approaching a breakthrough... though that may just be because Mr. Gordon kept dragging me off for extra training.
"In short, I am in excellent physical condition. A few low-star Monsters are nothing to worry about."
Isis frowned. "Why do you seem so desperate to enter the Arena Challenge? You're even talking faster. Francesca says people do that when they're hiding something and rushing to convince someone else."
Altaïr fell silent.
Senior Francesca, what exactly have you been teaching her?!
Altaïr nearly broke out in a cold sweat. He forced himself to control his expression and put on a look of exasperated amusement. "Don't force that sort of analysis onto everything. The Guild Manager is one of the highest-ranking members of the Guild, second only to His Immenseness. Can I really go back on my word to him so casually?
"Besides..."
After a brief pause, Altaïr released a heavy, frustrated sigh. "It's been almost a month since the Radiant Dragon Hunt. I haven't gone on a single Hunt since then, and I've barely had any chance to practice with my sword. I'm starting to feel as though I'm terminally ill."
At this point, Altaïr's frustration was entirely genuine.
Throughout that time, Isis had watched him like a hawk and constantly invoked his "unresolved injuries" to rein him in. It had left him thoroughly fed up.
Confronted with Altaïr's outburst, Isis visibly retreated. She turned her head away and muttered, "I'm only worried something might happen to you..."
Seeing her look so aggrieved, Altaïr did not know what to say.
Just then, the front door opened. Amos stared at the pair without expression. "Do you two enjoy standing outside the house and talking that much? Hurry up and come in."
Amos's arrival gave both of them an escape from the awkward moment, and they hurried inside.
The table was already covered with the dinner Amos had prepared. Just as the two were about to fetch their utensils, he stopped them.
"So, how did the checkup go this time?"
The Old Hunter remained deeply concerned about the health of Altaïr, the last disciple he had taken on.
Before Altaïr could answer, Isis launched into a rapid, thorough account of everything the director had said about the checkup. She also told Amos that Altaïr was going to participate in the Arena Challenge.
She hoped that Amos, with his wealth of experience and broad perspective, could offer them some advice.
Amos first glanced at Altaïr.
Unlike Isis, who had only met the Guild Manager a handful of times, Amos and the Guild Manager were old acquaintances.
From what Amos knew of the Guild Manager, the man would never invite a High Rank Hunter to enter the Arena Challenge merely as a publicity stunt. At most, he might send an idle High Rank Hunter to teach a class at the Training Camp.
Altaïr was almost certainly itching for a fight or eager to practice some new moves.
Amos did not expose his little trick. After considering the matter, he said to Isis, "A cautious approach is the right one. Altaïr's condition is unique, with no comparable case to use as a reference. As long as it does not worsen, leaving it alone is the most reasonable course of action.
"As for the Arena Challenge, let him participate if he wants to. A little exercise and movement might even help his body absorb and integrate those things more smoothly."
With that, Amos turned back to Altaïr. "But you still need to be careful. Whether it is the Frenzy Virus, the Qurio, or something else, its activity rises sharply when its host enters combat.
"The things inside you may behave the same way. Pay close attention, and if anything unexpected happens, stop the match immediately. Don't worry about losing face by withdrawing in front of the crowd. A little embarrassment is nothing next to your life."
"Then... shouldn't he be avoiding combat even more?" Isis could not help blurting out.
Amos shot her a glance. "Unless you can convince him to retire here and now, he will return to the hunting grounds sooner or later.
"Wouldn't it be better for any problem to reveal itself first in the controlled environment of the Arena than out on a hunting ground full of deadly threats?"
Isis opened her mouth, but ultimately nodded in silence.