Extreme burst and sustained burst are completely different optimization directions. In the battle against Upper Rank Five Gyokko, Kiyokawa Izumi had exposed many problems.
Perhaps because this body was not yet an adult and was still in its growth phase, its speed, strength, and endurance weren't particularly outstanding.
There was still a lot of room for improvement in his base stats; he hadn't reached his theoretical limit yet.
The most disappointing aspect was his endurance!
The combined usage time of the Third Form and Fourth Form didn't even exceed five minutes.
At his Peak, Kiyokawa Izumi might be able to easily kill a Lower Rank, but against any Upper Rank—even Gyuutarou, the lowest-ranked among them—he couldn't achieve a quick victory.
His strongest state wasn't enough to break the deadlock; he might achieve suppression, but barring any surprises, his condition would quickly decline.
Then, he would naturally be killed.
Once caught in a war of attrition or a prolonged battle, his defeat was certain.
Whether it was the Third Form or the Fourth Form, the consumption of physical stamina was immense.
If his combat power in his normal state was ten, then his theoretical maximum was thirty.
After switching his Breathing Technique, because his Swordsmanship Rank was already high and his base stats had significantly increased, even a casual strike could reach a combat power of thirty-five or even forty.
Kiyokawa Izumi actually hesitated about whether to abandon Dark Breathing.
The boost to physical functions from the Seven-Day Breathing Method was massive and obvious; however, using it for the first time while injured meant his performance was certainly far from perfect.
Focusing on the Seven-Day Breathing Method might still not solve the issue of insufficient stamina, but his strength would significantly increase in the short term.
The price was that his upper limit would be locked to a certain extent.
He was just a user, after all, and might not even be able to instantly increase his lung capacity to four times the normal amount, let alone continue developing it along the original concept.
Six, eight, or even ten times sounded tempting, but it was impossible for him.
Once he reached a limit, his strength would remain stagnant for a long time.
If he wanted to improve further, he could only consider the three-piece set.
The Demon Slayer Mark went without saying, but he still hadn't figured out the unlocking conditions—was his body temperature not high enough, his heart rate not fast enough, or his will not firm enough?
Kiyokawa Izumi might not be able to become the first swordsman of this era to unlock the Demon Slayer Mark, ultimately because the unlocking conditions were too vague.
As for the Transparent World and Scarlet Blade, they were even more difficult for an ordinary person like him who lacked talent.
Once he abandoned his original Breathing Technique, Kiyokawa Izumi would fall into a Bottleneck for a long time.
The same applied to his Swordsmanship Rank.
Rank Five seemed to be the limit for an ordinary person.
Examining himself, he realized he wasn't strong enough—not nearly enough!
After a brief hesitation, Kiyokawa Izumi finally made up his mind to stick with Dark Breathing as his primary technique.
He believed that the Fourth Form he created was very close to the Transparent World; giving it up like this would be too much of a pity.
When he first created the Third Form, he had referenced his Big Brother's high-speed dash when performing his Profound Truth, as well as Kochou Shinobu's short-range dash while using Insect Breathing.
After all this time, the Segmented Burst he used back then now seemed crude and unrefined.
As a greedy adult, he wanted both extreme burst and sustained burst!
Soundless Three Stage could also become Soundless Six Stage, or even a nine-strike combo—he wanted to completely abandon the Segmented Burst breathing and fix the final flaw in this Move.
The Gyokko he faced ultimately had melee skills far inferior to the upper rank one and Upper Three, so he hadn't noticed the obvious flaw in Soundless Three Stage.
When breathing forcefully, if the attack was blocked or the breathing was interrupted, the Move wouldn't work, and the excessive breathing might even backfire on him.
Never mind upper rank one or Upper Three; using this Move against Douma would also be suicidal.
His Blood Demon Art countered Breathing Techniques extremely well.
If Kiyokawa Izumi were lucky enough to engage in close combat and dared to use burst breathing around him, he would only inhale poisonous Ice Crystals—Douma's blood was highly toxic, and after freezing, it turned into Ice Crystal Powder spread through his Iron Fans.
Daring to use Soundless Three Stage in front of him was no different from seeking death.
Kiyokawa Izumi's short-term plan was to optimize the rhythm of Dark Breathing, make the Third Form more sustainable, and then create a Sixth Form focused on thrusting.
Finally, there would be his unique Profound Truth, the Seventh Form under extreme burst.
Once he achieved this, his self-created Breathing Technique would be basically complete.
Its strength certainly couldn't compare to the ceiling that was Sun Breathing.
But if he could push it to the limit, even in his base state, he was confident he could solo the bottom three Upper Ranks.
If he couldn't awaken the three-piece set, his limit would only be this much.
It wasn't weak, but it certainly wasn't strong.
Reaching his theoretical limit, Kiyokawa Izumi estimated he could trade ten Moves with Kokushibou—provided the latter didn't get serious and didn't enter his Second Phase right from the start.
Against a second or even Third Phase Kokushibou, who in their base state could trade three or five Moves with him?