Had Tanjiro and his sister Nezuko not crossed paths with Giyu Tomioka, their fate might have mirrored that of Gyutaro and Daki.
Warning: This article contains spoilers for episode 11 of Kimetsu no Yaiba Season 2 anime.
The backstory of the upper moon siblings unveiled in episode 11 of Kimetsu no Yaiba Season 2 has sparked profound contemplation among audiences. Both sets of siblings rely on and care for each other, yet the upper moons represent a darker, more sinister version of Tanjiro and Nezuko. Through the discourse of nature versus nurture, Kimetsu no Yaiba underscores the importance of upbringing within a family, contrasting the nurturing love of Tanjiro and Nezuko's family with the hatred and loneliness experienced by Gyutaro and Daki.
The final episode of Season 2 dedicates a significant portion of its runtime to Gyutaro's harrowing memories of his human life. The anime adeptly explores these recollections to elucidate why Gyutaro and Daki turned into demons and to evoke sympathy from the audience. The prevailing sentiment among viewers towards this episode is one of pity and sadness for the two antagonistic characters, while also acknowledging Tanjiro's fortunate encounter with the Water Pillar.
Gyutaro's childhood clarifies his envy towards Tengen Uzui's physical perfection. He harbors resentment and disdain towards anyone born beautiful and beloved, as his own grotesque appearance is an inherent deformity from birth. In contrast, his sister Daki, or Ume, is born exceptionally beautiful. Ume's presence alleviates Gyutaro's insecurities; he takes pride in and strives to protect his sister. A striking parallel emerges not only in the protective bond between siblings but also in Gyutaro's discovery of Ume's immolation, reminiscent of Tanjiro's horrifying realization of his family's massacre.