Superbia Squalo tells Tsuna and his Guardians to burn Yamamoto's last moments into their minds. Yamamoto, however, gets up and, despite Squalo telling him to lie back down, states that the Shigure Soen Style was flawless, and completely invincible. Squalo then attacks Yamamoto, announcing that he would cut out Yamamoto's "insolent" tongue first. Yamamoto then has a flashback to him and his father, his father bringing him lunch and asking him how the Shigure Soen Style was going. Yamamoto's dad expresses his surprise at Yamamoto being the best at the 8th form, and proudly states that they were alike. Yamamoto's father then explains that the 8th form, Shinotsuku Ame, came into being when a "young successor" was rescuing a good friend of his at the brink of a typhoon, and that it was the last form to come into existence.
In the present, Yamamoto was hit by Squalo's attack, but still gets back up. Squalo asks Yamamoto what he was here for, the latter replying that it was the Shigure Soen Style. Yamamoto then gets into a stance, Squalo triumphantly stating that he knew the stance, charging towards Yamamoto and yells at him to execute the supposed 8th form, Autumn Rain, but Yamamoto unleashes a different attack, Pouring Rain (Shinotsuku Ame), lacerating Squalo. Levi A Than narrows his eyes comically and asks what just happened, and Squalo asks Yamamoto if he used a style other than Shigure Soen; however, Yamamoto replies that it was still the Shigure Soen Style, adding that the technique was created by his father.
Reborn then states that he understood, and that for the Shigure Soen Style, to undergo succession was to undergo change. Reborn explains that Squalo fought the other apprentice of Yamamoto's dad's master, who created a different eighth form than Yamamoto's dad. Basil expresses his confusion, asking if there were countless Shigure Soen Style forms. Reborn, however, states that it was the opposite, and that the style hadn't died out by now was a miracle, and that change not only consisted of progression, but regression as well. Reborn explains further, stating that only the strong forms with talent stayed, and the ones that were created without spirit and passion died out; thus, if there were no more people that had spirit and passion for the sword, the Shigure Soen Style would die out, the style being a sword of ruin.
Squalo asks Yamamoto if there were any more unknown styles, Yamamoto replying in the negative. Squalo triumphantly shouts that he had already seen through Yamamoto's eighth attack, but Yamamoto states that he would have to shown Squalo the Shigure Soen Style's 9th form. Reborn and Dino realize that Yamamoto was creating a new style, and that if the Shigure Kintoki didn't change into a steel sword (the sword only changing forms if used in the Shigure Soen Style), Yamamoto would fail, making the strike a test for Yamamoto to see if he was really the worthy successor. Squalo then charges forward, Mammon wondering if they would get to see Scontro di Squalo, the technique that Squalo used to defeat Tyr, the previous Sword Emperor and Varia Boss. Yamamoto then charges forward as well, beginning to unleash his 9th form, which resembles a baseball stance.
Note: Bold + Italicized = First Appearance