With a whup-whup sound of beating the air, the tilt-rotor aircraft hovered.
There was no conspicuous movement within the Fairy Circle below.
“FC investigation unit, begin airborne drop.”
From the tilt-rotor aircraft loitering at an altitude of about 100 meters, four four-legged, two-armed Jumpers leaped out.
The Jumpers extended all six of their limbs to stabilize their falling posture, while making short gas bursts to reduce their falling speed.
Because they had been lightened by stripping away unnecessary functions, even something like gas bursts could provide sufficient deceleration.
“All four Jumpers have landed on the ground without issue.”
Using their relatively long limbs deftly compared to their bodies, they absorbed the impact on landing.
The Jumper unit descended onto a grassland thick with greenery.
“No movement detected. Heat-source detection shows no abnormalities.”
“Feels like we just do a lap first?”
“Yes-affirmative, Commander Ma’am. After we secure safety, we will release a drone with a mana meter integrated. Since this is a site with conspicuous non-scientific changes, I would like to discover some kind of discrepancy.”
From the mana meter reactions recorded so far, it had been confirmed that some particle-like or energy phenomenon called mana showed variations in density.
Roughly speaking, the closer to the ground, the higher the concentration, and even at the same altitude, there were differences depending on location.
Even in the same place, the density could change over time.
Its precision was not good, but it was an unknown measuring instrument called a mana meter.
The reproducibility of the observations had also been firmly confirmed.
“No abnormalities. FC investigation unit, begin patrol.”
After landing, the four Jumpers that had been collecting information around them began to move.
From near the center of the Fairy Circle, they expanded their sweep range in a spiraling pattern.
“There appears to be no particular anomaly in plant species either. All of them are plants already confirmed in the <Demon Forest>. There are no anomalies on passive sonar. Infrared detectors also show no noteworthy reactions.”
They had them walk and investigate within an area of about a 5-meter diameter.
Other than the issue that plant growth speed was fast, they could not find anything that looked like an abnormality.
“Dropping a fixed emplacement composite sensor.”
From the tilt-rotor aircraft overhead, a sensor was dropped. The freely falling sensor drove the anchor on its underside into the ground with its own weight, extended stabilizing legs, and fixed itself in place.
“Sensor fixation complete. Beginning information collection.”
A fixed emplacement sensor was dropped into the region where provisional safety had been secured, and more detailed information collection began.
“No suspicious movement within a 50-meter radius around us... and. Shall we move the Jumpers?”
“Yes-affirmative, Commander Ma’am. FC investigation unit, begin independent movement.”
Since sensor data confirmed there were no threats around them, the four Jumpers were moved in different directions.
“What we particularly want to confirm is this tree that is growing rapidly inside the Fairy Circle. We also confirmed several trees of the same kind on the outer edge.”
“Is it because it grew so fast? The trunk is green.”
“Yes-affirmative, Commander Ma’am. Based on the characteristics of its form, it appears to be a tall tree similar to the beech family. It is a species commonly confirmed in the <Demon Forest>.”
The trunk—more precisely, the bark—became brown and hard as time passed. Young branches had not had time pass yet, so their skin also remained green.
This rapidly grown tree being observed now had only had about a week pass.
Because of that, it had a trunk of considerable thickness, but the whole thing still retained green coloration.
It was a highly uncanny appearance.
“Hm... I didn’t get it just hearing about it, but...”
“When you see it on video, it really does have the features they described.”
“Yeah. When they said ‘a green tree,’ I thought, ‘Isn’t that obvious?’ but this is what they meant.”
What she, Eve, was referring to was a story about a monster in the <Demon Forest> that had come up while gathering information in Northend City—fairly famous, and troublesome.
“Want to take a guess?”
“Yes-affirmative, Commander Ma’am.”
That monster’s name was the False-Green Treant.
It was a rather special monster in which a tree had become a monster and begun predatory activity.
“FC investigation unit, move FC-1 toward the target.”
With a metal mace placed in its work arm, one Jumper was brought closer to the treant.
So they could respond immediately if anything happened, the remaining three held their multi-stage electromagnetic cannons (coilguns) at some distance.
When the Jumper got reasonably close, there was a rustle of leaves.
“Wind speed is under 1 meter per second. There is almost no wind.”
“I see?”
Leaf rustling when there was no wind.
Meaning the branches had moved by some kind of force.
The Jumper moved closer.
The moment its body entered beneath the crown—
The surrounding branches, as if to wrap inward toward the trunk, lunged at the Jumper.
The command AI inside the transport aircraft waiting overhead observed the scene in detail.
It operated the Jumper and reacted immediately.
With the metal mace it had raised, it batted the branches away.
At the same time it braced its four legs and retreated {N•o•v•e•l•i•g•h•t} out of the attack range.
However, that movement was obstructed by tree roots that burst out of the ground.
Because the Jumper was a lightweight structure, its mass was far smaller than it looked.
Tree roots tangled around the legs planted on the ground, and it lost its balance.
Even so, the Jumper’s mobility performance was high.
With gas bursts, it forced a retreat even while off-balance.
At the same time it swung the metal mace around and recovered its balance.
Twisting the frame, it took distance from the False-Green Treant in a way that truly looked like it was hopping.
“Whoa! The tree really moves!”
“Why it can move is unknown. In appearance it is no different from a tree, and there are no heat sources like muscle tissue confirmed.”
A treant was a tree monster.
According to the collected information, if you cut it down, it could apparently be used as timber just like a normal tree.
It also had a magic stone inside, and its activity would stop by removing it, or by destroying it.
However, defeating a treant that launched attacks with branches and roots was not easy.
The easiest way to defeat it was to pierce through the trunk with a powerful blow and precisely shatter the magic stone, but only a small portion of adventurers could do that.
Normally, you detoured so you would not be attacked.
Because of that, treant materials were extremely scarce.
“Trees suspected to be treants: three others. Since the features match, we will assume they are treants. Setting a safe operating range. Deploying the mana meter drone.”
After securing safety, they released a drone equipped with a mana meter.
They formed a spherical formation with escort drones, placing the mana-meter drone at the center.
This way, even if some kind of attack occurred, the first damage would occur to the outer drones.
“Measurement response: beginning recording.”
By analyzing the vibration amplitude of the mana meter, they could record the rough mana concentration as a spatial concentration.
It was a provisional approach to see whether there was a mana change inside the Fairy Circle.
“Mana density fluctuates up and down in the <Demon Forest> to begin with, but the change is conspicuous here.”
“Is it?”
<Ringo> displayed a three-dimensional concentration-distribution map for explaining to Commander Ma’am. It converted the mana-density gradient into color transparency for each measured point in space.
When they placed measurements from another location side-by-side with the measurements inside the Fairy Circle, the difference was obvious at a glance.
“Inside the Fairy Circle, mana density near the ground seems to trend high. Yes—almost as if mana is seeping out of the ground. And around the treants, the mana density appears lower compared to the surroundings.”
“Oh, you’re right. The sample size is small so we still can’t really say, but...”
“We can infer that there seems to be some relationship between monsters and mana density.”
While they talked like that and observed the investigation progress—
“Slime emergence has been confirmed.”
“Wait, seriously?”
The all-around camera on the fixed emplacement composite sensor recorded a slime oozing up from the ground.
