A fan theory posted on the Boruto subreddit by user Significant_Shop_735 suggests that Sumire Kakei may play a crucial combat role in a future climax of Boruto: Two Blue Vortex. According to the hypothesis, Sumire could end up wielding Boruto Uzumaki's upgraded Kusanagi sword during a critical confrontation, mirroring Hinata Hyuga's famous intervention during the Pain arc in the original Naruto series.

The theory relies on details from Chapter 28 of the Boruto: Two Blue Vortex manga, which established that the upgraded Kusanagi blade features a specialized chakra registration mechanism. Only three people are registered to use the sword safely: Boruto Uzumaki, Sasuke Uchiha, and Sumire Kakei. Anyone else attempting to pick up or use the weapon suffers severe chakra drainage, rendering it unusable for unauthorized individuals.

Because Sumire was directly involved in repairing and enhancing the blade using instructions provided by Kashin Koji, she possesses intimate knowledge of its secret materials and inner workings. The fan post emphasizes that this detail must serve a purpose in the story. If Boruto is knocked down or separated from his sword while fighting powerful foes like the Shinju leader Jura, Sumire would be the only available ally capable of picking up the weapon.

The author further argues that Sumire's bond with her summoned beast Nue provides her with sufficient chakra reserves to hold off an enemy and sustain powerful abilities. Rather than functioning as mere fan service, stepping into battle with Boruto's blade would give her character a genuine moment in the spotlight after long serving primarily in a supportive scientific role.

The proposed scenario creates a thematic parallel to the classic Naruto storyline, where Hinata Hyuga stepped forward to defend Naruto Uzumaki when he was pinned down by Pain. In the same way, Sumire—who has quietly supported Boruto from behind the scenes while remaining immune to Eida's Omnipotence—could step up in his moment of need using his own weapon, providing a major narrative payoff in future manga chapters.

Currently in the manga, Boruto is battling Jura alone on the front lines using Sasuke's former sword, which was inherited and modified during the timeskip. Whether Mikio Ikemoto and Masashi Kishimoto intend to give Sumire a combat role remains unconfirmed, but fans continue to analyze the chakra registration mechanic as a potential setup for upcoming story developments in the Two Blue Vortex series.

Cover: NARUTO & BORUTO Official Site

Why Sumire Could Wield Boruto's Sword in a Critical Battle, According to Reddit Fan Theory

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