Shun sat cross-legged in the underground secret room of the Hokage Building, with the Flying Thunder God Technique scroll, left by the Second Hokage Tobirama, spread out before him. The dense annotations on the scroll revealed countless attempts and failures by predecessors.
"The first hurdle, advanced Fuinjutsu. No wonder so many people couldn't learn the Flying Thunder God."
Fuinjutsu is an application of Yin and Yang Release, with an extremely high learning threshold, and advanced Fuinjutsu is only the first hurdle for the Flying Thunder God.
"The second hurdle is perception, requiring the ability to remotely communicate with the Flying Thunder God Mark using Mental Energy, thereby activating a reverse Summoning Technique to summon the user to the marked location."
If he relied on Divine Eye, it should meet this condition, but the inability to use it in a normal state would be a significant drawback.
"The third hurdle is spatial talent. The Summoning Technique uses a blood contract + summoning formula to achieve cross-spatial summoning. But the Flying Thunder God Mark is just Chakra so it requires stronger spatial talent to achieve one-way perception and traction."
His finger gently traced the text on the scroll, surprised by how many learning hurdles the Flying Thunder God had.
Shun only knew low-level Fuinjutsu, and advanced Fuinjutsu was his weakness, so he was stuck at the first hurdle.
At this moment.
The door to the secret room was gently pushed open, and Tsunade's figure appeared at the doorway, her blonde hair flowing like molten gold in the candlelight.
Her voice carried a hint of reproach. "I heard you've been locked in here for two days, not even going to the Military Police Force?"
Shun didn't look up, still staring at the scroll. "I've roughly understood the operating principle of the Flying Thunder God, but this isn't a Body Flicker Technique in the traditional sense, its essence is a combination of Advanced Fuinjutsu + Advanced Perception + Advanced Spatial Talent."
Tsunade raised an eyebrow and sat down beside him. "Are you encountering any difficulties?"
Shun finally looked up, pointing to a complex jutsu pattern on the scroll. "I lack knowledge of Advanced Fuinjutsu, so I don't understand the Fuinjutsu diagram here."
Tsunade leaned in to examine it, her hair falling onto Shun's shoulder, carrying a faint fragrance.
"This jutsu is a variant of the Uzumaki clan's Fuinjutsu, composed of multiple layers of sealing formulas stacked together."
"The first layer, the lowest layer, this jutsu serves to store Chakra."
"The second layer seals the reverse Summoning Technique formula. Pay attention to this node, it's connected to the first layer."
"The third layer seals a barrier-specific circuit. It should act as an alert, able to perceive the spatial environment within 2 meters."
"The fourth layer seals a self-destruct module. If forcibly broken, it will self-destruct."
"The fifth layer seals a communication formula. It should act as a switch."
"The sixth layer seals a charging module. When the Flying Thunder God Mark's Chakra is depleted, it needs to be recharged."
Shun suddenly grabbed Tsunade's wrist and asked, "Tsunade, you even know this?"
Tsunade gently pulled away and said, "My grandmother was the princess of the Uzumaki clan. I mastered this kind of Advanced Fuinjutsu when I was 12."
She pointed to the most complex part of the scroll. "Advanced Fuinjutsu requires extremely high Chakra control to compress Chakra to its extreme, almost to the point of solidification."
Shun's eyes lit up. "Compressing Chakra to its extreme!"
Tsunade sighed helplessly, "Come to my room tonight, and I'll teach you Chakra compression techniques. Now, your eyes are bloodshot, you need to rest."
Shun wanted to argue but couldn't help but yawn.
...
That night, Shun appeared in Tsunade's bedroom on time.
Tsunade took out the First Hokage's green crystal necklace and said, "The higher the quality of Chakra, the more realistic the things created become, like Kekkei Genkais such as Ice Release and Crystal Release. This green crystal necklace was made by my grandfather, Hashirama, using his Chakra. Feel the Chakra within the green crystal."
Shun activated his Mangekyo, observing the green crystal with Divine Eye.
"The quality of each Chakra is very high, and every twelve Chakra are arranged in an orderly pattern, like countless military formations composed of Chakra. The arrangement of these military formations is extremely tight and orderly, hard to imagine."
Tsunade began to explain, "You have the Mangekyo Sharingan, so your Chakra quality is also very high. The difference lies in the arrangement of the Chakra."
Shun observed intently, then a ball of Chakra formed in his palm, but it was far less solid than Tsunade's.
Tsunade evaluated without mercy, "Your Chakra quality is even higher than mine, but your control over Chakra is too low, so your Chakra is very loose. You need to make each of your Chakra like obedient soldiers before you can proceed to the next step."
Shun closed his eyes, and when he opened them again, the Mangekyo in his eyes began to spin. The Chakra in his palm immediately arranged itself obediently.
Tsunade praised him, which was rare, "You're cheating with your Mangekyo's Ocular Power. Never mind. As I said before, stack the six layers of the Flying Thunder God's Fuinjutsu together."
With Shun's continuous output of Mangekyo Ocular Power, the first Flying Thunder God Mark Kunai was successfully created.
Immediately after, he formed hand seals, summoned a Shadow Clone, and had the Shadow Clone take the kunai and run out of the room to test its perception.
As the Shadow Clone ran further and further, Shun's perception of the Flying Thunder God Mark became increasingly blurry.
"If I don't use the Mangekyo Ocular Technique, once it exceeds 100 meters, I can't sense the Flying Thunder God Mark anymore. It's a bit lacking."
Shun activated his Mangekyo again, then summoned a Shadow Clone and had the Shadow Clone test the Flying Thunder God Mark. As a result, the Shadow Clone successfully teleported to the other side.
"You succeeded?"
Watching the Shadow Clone disappear, Tsunade unconsciously took half a step forward, revealing her fair calves.
Shun closed his eyes and mused, "I succeeded, but it requires Mangekyo assistance. Otherwise, my Flying Thunder God Mark can only be used within 100 meters."
After speaking, he walked towards Tsunade, his hands beginning to move naughtily.
Tsunade slapped his hands away but couldn't hide the curiosity in her eyes.
"It's good that you succeeded, you can continue practicing later. By the way, with Mangekyo assistance, how far can you use the Flying Thunder God?"
Shun smiled confidently, his gaze piercing through layers of trees. "My Mangekyo Ocular Technique: Divine Eye, you can think of it as an enhanced Byakugan, capable of seeing 72 kilometers away. So after using it, I can use the Flying Thunder God within a 72-kilometer radius."
Tsunade pinched his nose and said, "This is already further than Minato's Flying Thunder God. By the way, I helped you complete the Flying Thunder God, how are you going to reward me, you little pervert?"
Shun picked up Tsunade and said, "I learned the Flying Thunder God precisely so I could come and reward you often. My good Tsunade."
Upon hearing this, Tsunade wrapped her arms around his neck and kissed him passionately.