Due to his sheer strength, he accidentally killed (incapacitated in the anime) an opponent during a match and soon after dedicated his life to religion. At his Family's moment of crisis however, he gave himself three minutes to fight and managed to save his friends when they truly needed him. The First Sun Guardian and Ryohei, Vongola Decimo's Sun Guardian have a strong resemblance in their weapon of choice, their way of fighting, their personalities and their physical features.
When Tsuna and the others return to the past along with Uni to train before battling with the Millefiore, Uni summons Vongola Primo from the Vongola Ring and was told that the first Guardians of the Vongola Family will observe henceforth if they are worthy enough to inherit Vongola's true power or not. At night, he appears from the Sun Vongola Ring in front of Ryohei at the same time as Giotto's other guardians done the same to the respective guardians. After introducing himself, he commented that this must be based around the will of God and said everything depends on Ryohei's hard work while he's judging him.
After Skull was defeated, he appeared in front of Ryohei and the others and deemed him worthy to inherit the power of the Sun Guardian along with Alaudi, who also deemed Hibari worthy. As Hibari requested Alaudi to fight him, he commented that Hibari is just like what Alaudi used to be like.
Later, at Namimori Shrine, he along with other the Guardians and Primo meet to discuss the trials so far, and the ones yet to come. All of them look worried since the next trial would be Demon Spade's succession test. At Kokuyo Land, he along with Giotto and the other guardians watched Demon Spade's trial from afar and one of Guardians who opted to stop Demon, reminding Giotto that Demon has taken a different path from them since the very beginning, but Giotto told them just to wait and watch to determine the true worth of the 10th Generation Vongola Family.
After Demon Spade's trial finished, he along with the other Guardians and Giotto returned to the Vongola Rings.
While Tsuna fought Byakuran, he appeared, along with Giotto and the other guardians from the Vongola Rings after witnessing Tsuna's resolve, encouraging them not to give up.