The Tesseract was the container for the Space Stone, one of the six Infinity Stones in the Marvel universe, also known as the Cosmic Cube.
The Tesseract possessed the power of space, capable of spatial teleportation and opening dimensional gateways.
For example, in the original timeline of this universe, the Red Skull activated the Tesseract at the end and was teleported to an unknown location.
In the Avengers timeline, Loki used the Tesseract to create a wormhole, allowing the Chitauri army and warships to pour onto Earth continuously.
When Uchiha Kazuhiko learned the mission was set in the era of Captain America, he had already marked the Tesseract as a must-have trophy. He anticipated what kind of surprise the Tesseract, one of Marvel's top-tier treasures, would bring him.
Thud!
Steve found an opening, striking the Red Skull with his shield. The Red Skull cried out in pain, flying backward and crashing into the Valkyrie's control panel.
Struggling to his feet, the Red Skull inadvertently pressed a button on the control panel with his right hand, causing the Tesseract to rise from within the console, exposing itself to all three.
Cornered, the Red Skull grabbed the Tesseract, attempting to absorb its energy, hoping to gain the power to defeat Steve.
Guided by the Red Skull, a powerful spatial energy surged from the Tesseract, enveloping his entire body.
A look of joy appeared on the Red Skull's face, thinking he had mastered true god-like power. Just as he was about to boast, he suddenly screamed in agony. Within mere seconds, the Tesseract teleported him to an unknown world.
As the spatial energy subsided, the Tesseract fell from the air onto the Valkyrie's cabin floor. It melted through the metal fuselage and began falling towards the ocean below.
Ding dong! Congratulations, Host, on completing the Black Iron Rank mission [Save New York]. Reward: 12 System Gold Coins, 11 Mission Points.
Ding dong! Mercenary mission complete. The Host may freely choose to leave the mission spacetime within one day. Exceeding the time will result in forced departure. You may also spend gold coins to remain in the mission spacetime at a price of 1 gold coin/day. Time remaining: 23 hours, 59 minutes.
With the mission successfully completed, Uchiha Kazuhiko could leave this spacetime at any time.
He glanced at Steve, who was trying to control the Valkyrie, and immediately opened the Fourth Gate of the Eight Inner Gates.
"Goodbye, Steve."
Without waiting for a response, he tore open a section of the metal hull, kicked off forcefully against the airframe, and shot like a missile towards the freely falling Tesseract.
When he was only a dozen meters above the sea, Uchiha Kazuhiko reached the Tesseract. He grabbed it, immediately stored it in his system space, and without a second's delay, mentally commanded his return. Just as he was about to hit the water's surface, he appeared back in the inn room in the Cloud Village.
"Whew, that was close..."
Uchiha Kazuhiko wiped cold sweat from his brow. Falling from such a height at high speed, the impact with the water would generate tremendous force. Even with his physical constitution, it would be hard to withstand.
Let alone searching for the Tesseract in the ocean; surviving the impact itself would have been uncertain.
Fortunately, Lady Luck was on Uchiha Kazuhiko's side. He successfully obtained the Tesseract and returned safely to the Naruto world.
After resting briefly, Uchiha Kazuhiko, as usual, began reviewing the gains from this mission.
Due to space constraints, he had recycled most of the Hydra soldiers' weapons within the mission spacetime itself.
He had only kept fifteen magical energy rifles in his space. He recycled thirteen of them. Combined with the mission reward, this mission netted him a total of 243 gold coins.
"System, purchase [Low-Grade Evil-Cleansing Pill]."
With gold coins in hand, Uchiha Kazuhiko immediately spent 25 coins to buy the pill that could neutralize Orochimaru's Cursed Seal and consumed it.
As the medicinal potency dissolved, a cooling energy rose from his abdomen, flowing through his limbs and bones. It not only expelled the Cursed Seal Orochimaru had placed on his arm but also began disperse to the excess waste and impurities within his body.
By the time the Low-Grade Evil-Cleansing Pill's effects were exhausted, the waste and impurities in Uchiha Kazuhiko's body were completely purged.
His entire body felt light and transparent, experiencing an unprecedented level of comfort.
"Truly worthy of a mid-tier Black Iron rank pill. The effects are extraordinary."
After checking his physical condition, Uchiha Kazuhiko was full of praise for the pill's efficacy.
Having eliminated the hidden danger left by Orochimaru, Uchiha Kazuhiko turned his attention to his greatest gain from this mission the Tesseract.
[Tesseract]: The sealed container for the Space Stone. Possesses near-infinite energy and spatial power. Recycling price: 200,000.
"Two hundred thousand..."
Seeing the astonishing value of the Tesseract, Uchiha Kazuhiko was momentarily stunned by this immense fortune.
Coming to his senses, his face flushed red, and his breathing grew heavy. Just as he was about to recycle it, the system's mechanical voice suddenly sounded.
"Host, an item capable of enhancing system functions detected: [Tesseract]. Use it to upgrade the system?"
The system's voice was like a bucket of cold water, snapping Uchiha Kazuhiko out of his excitement. His bloodshot eyes regained clarity, and rationality returned.
After taking over a dozen deep breaths, he finally calmed down completely.
"System, if I use the Tesseract for an upgrade, what improvements will I get?" Uchiha Kazuhiko asked.
Although the Tesseract could be exchanged for a vast number of gold coins, the Pan-Universe Mercenary System was Uchiha Kazuhiko's most core asset. If it could enhance the system's capabilities, Uchiha Kazuhiko would naturally not begrudge these external possessions.
"After the system upgrade, some space-related functions will be improved to a certain extent. Furthermore, upon accumulating sufficient energy, the system can permanently detach from this spacetime and travel to a new, higher-level spacetime."
After all, the Naruto world was a low-level world.
Even with strength surpassing Kaguya Ōtsutsuki, he would be nothing more than an ant in those high-level worlds.
Only by entering high-level worlds could he grasp more resources, continuously break through his limits, until he surpassed everything and mastered his own destiny.
"System, use the Tesseract to upgrade the system level."
Uchiha Kazuhiko made his choice between immediate gain and future potential, commanding the system to absorb the Tesseract.
"Confirmed absorption of special item [Tesseract]. System upgrading. Time remaining: Unknown. All functions remain operational during the upgrade."
The series of upheavals had sent Uchiha Kazuhiko's emotions on a rollercoaster. He suddenly felt very tired and thus abandoned his original plan to explore the Cloud Village.
He began cultivating frantically, exhausting himself completely, then took a bath and fell into a deep sleep.