Lintukodossa - Lintukoto

I have no idea how to properly put this into words, but one of my favorite things in Demon Slayer is like. The sibling switch up dynamic. Tanjiro is used to being the eldest. He's a big brother, the responsibility of being The Eldest is ingrained into his very bones, and even with his friends, despite being younger, he's still used to being more mature than Inosuke, Zenitsu, and even Genya sometimes. Which is why I really enjoy when he's thrust into a dynamic where he's thrust into the younger sibling role, like with Rengoku or Giyuu (or Mitsuri to a degree). He wants to be respectful to them since they're older, but like. They're all kinda goofy in their own ways, they're too casual for Tanjiro to go Full Polite and Respectful Young Man. He has to bully them back a little bit the way one would an older sibling and it's funny that that's just a little out of his wheelhouse since he's used to being the oldest. In the same vein, Giyuu and Shinobu were both younger siblings who dearly loved their big sisters and now that they're older, they've also been handed the responsibility of mentoring someone younger. Giyuu ran away from this for as long as he could because his guilt and shame kept him from seeing himself as someone capable of ushering in a new generation. It also meant that he ran away from being understood until Tanjiro got through to him. Shinobu, I think, also tends to be closed off, but she saw this little girl that her sister cared about so much and threw herself into training her. And she did find understanding with Kanao, because Kanae had become a big sister to them both. Something about family being blood and bond. Something about Tanjiro being the one to scold Rui about the family you create being just as important as the one you were born with. Argh

Kimetsu no Yaiba Settei Collection Book 1-part 3

Genya: What is your biggest weakness? Muichiro: I can be uncooperative. Genya: Can you give an example? Muichiro: No.