Darkness.
Cold.
Silence.
In the deep sea abyss, even time itself seemed to lose meaning.
"Lug!"
Suddenly, a cry somewhere between a whale and a dolphin rang out, breaking the deep sea's original stillness.
Greninja opened its eyes, instinctively turning its head in the direction of the sound.
Soon, a pair of red eyes quickly approached from the distance, and in the blink of an eye, they were right in front of Greninja.
Greninja moved a bit closer on its own; this was the only thing it could "see" in the deep sea.
"Gren..."
"Lug~"
"Gre-nin."
"Iaaa..."
"..."
The two seemed to be communicating, and Greninja was clearly more excited than the other.
Soon, the red eyes shifted direction, and in the darkness, Greninja seemed to spot something and quickly followed those "red eyes" into the distance.
They swam diagonally upward. Although their speed wasn't slow, the distance must have been too great, and the deep sea too vast; from afar, they looked like two faint red glowing "worms" slowly inching along.
At some unknown point, Greninja caught a faint glimmer of light and finally saw its old friend clearly for the first time in a long while.
Calling it an "old friend" might be a bit much… because the Pokémon beside it was none other than the one with a clan bearing the title of "Guardian of the Seas".
Lugia!
Greninja was clinging to the purple dorsal fin on Lugia's back, being rapidly pulled forward by the Legendary Pokémon.
Some time passed. The light remained dim, but they had reached their destination.
The Kingdom of the Sea!
Passing through a spatial barrier that kept out the ocean currents, Greninja's vision suddenly brightened.
The strong light made it squint, slowly adjusting to the sudden change.
Soon, the Kingdom of the Sea came into clear view. SEea water bright as daylight, and uneven layers of colorful coral reefs.
All kinds of marine Pokémon swam about, in groups of three or five, each looking quite busy.
And when the Pokémon saw Lugia, Corphish and Kingler were the first to arrive and form up beside it.
"Pish!"
"KING!"
The voices of Corphish and Kingler weren't loud, but they quickly spread throughout the entire Kingdom of the Sea.
All the marine Pokémon turned their heads toward Lugia and Greninja.
Then, one cry after another rang out -from the massive Wailord to the tiny Wishiwashi, from the proud Milotic to the reclusive Wimpod- every single marine Pokémon lowered their heads to the ruler of the sea kingdom, Lugia.
Paying solemn respect!
"LUGIAAAAA~!"
The long, deep call echoed through the entire Kingdom of the Sea. At that moment, Lugia's majesty was fully revealed, unmatched and overwhelming.
Greninja stood beside Lugia, staring in awe at the scene before it.
This... was the Legendary, Lugia?
After the salute, the marine Pokémon remained still. Lugia called to Greninja once more and continued heading deeper into the Kingdom.
Only after Lugia left did the marine Pokémon, still in their respectful posture, raise(?) their heads and return to their tasks, as if it were routine.
Now that there was light, Greninja no longer had to hold onto Lugia to move forward.
Not to mention, after witnessing such a breathtaking scene, it didn't dare casually grab on again.
Greninja's own swimming speed wasn't slow, so the two Pokémon continued forward, one ahead and one behind.
After passing through the vibrant coral reefs, a massive undersea mountain suddenly appeared. The two Pokémon continued to swim upward and quickly reached the summit.
Above the summit was a massive platform, and at the far end of it stood a small man-made hill.
Atop the hill sat a giant, extremely primitive-looking chair.
The Throne of the Guardian of the Seas!
No explanation was needed. Lugia had already swum over and landed firmly on the throne.
The seat was neither too big nor too small, just the right size for Lugia to rest on.
Greninja followed along and naturally stood below, quietly waiting for Lugia's command.
Ever since it had been brought here by Lugia, it had spent a long time in the lightless, high-pressure trench of the deep sea.
Exactly how long, it no longer had any concept… but whether in that deep-sea trench or here in the Kingdom of the Sea, the surrounding Water-type energy was terrifyingly dense.
The deep trench even contained rare Dark-type energy found in the ocean.
These energies, under immense pressure, were forced directly into its body, constantly strengthening it passively.
When Lugia brought it into the realm, Greninja immediately realized.
The second phase of its training was about to begin!
At Lugia's command, Greninja descended onto the large flat area at the mountain's peak.
Just as it was wondering what would happen next, an enormous Wailord suddenly leapt up from below the mountain and landed on the flat ground.
Greninja's eyes widened in shock. It looked at the boundless Wailord, then turned toward Lugia, confirming that this wasn't a joke.
Lugia stared calmly back at it, locking eyes with Greninja, as if to say… 'That's right. Your opponent… is that big guy.'
"Gren..."
Finally, Greninja slowly turned its head and stared seriously at the massive Wailord, unsure where to even begin.
"LOOORD!!!"
Greninja stayed still, but the Wailord across from it clearly couldn't wait any longer.
Having just welcomed the Sea Guardian's return and now being summoned for battle, Wailord was ecstatic.
But when it learned that Lugia had ordered it to battle this little guy in front of it, intense jealousy instantly surged in its heart.
It didn't dare blame Lugia for underestimating it, so Wailord placed all the resentment on Greninja.
'Fine then! Let me show my full strength in front of the Sea Guardian!'
Water Spout!
Its power decreases as stamina drops, but at full strength, Water Spout was comparable to Hydro Cannon, the ultimate Water-type move!
And now, it surged forward, crashing down on Greninja like a tidal wave!
---◓---
The unending battles had begun. In the Kingdom of the Sea, there was no distinction between day and night.
Greninja began battling all kinds of marine Pokémon.
It experienced Wailord's vitality that could withstand the depths of black holes, Barraskewda's lightning-fast speed, Toxapex's fortress-like defense, Primarina's unmatched long-range attacks, and even the earth-shaking brute force of a mega-sized Swampert!
There were too many battles. So many that even Greninja couldn't remember how many it had won or lost.
Every time it collapsed and rested, it was because it had been defeated and lost consciousness.
At the edge of the battlefield, Milotic, Alomomola, Slowking, Luvdisc… every kind of healing and support Pokémon stood on constant standby.
Each time Greninja went down, they'd rush over one after another, healing it as if cost didn't exist.
From time to time, Lugia would even send down a mysterious energy from afar, sparking endless envy from the surrounding marine elites.
When Greninja opened its eyes again, the next opponent was already waiting in front of it.
Its mental and physical exhaustion would be completely gone, and with a body full of energy, all it wanted was to take down the enemy standing before it.
The battles… felt endless…