I was really worried about how they'd wrap everything up given the tone of the earlier parts, but the final battle and aftermath genuinely surprised me. The whole reincarnation epilogue felt like such a tonal shift that it left me conflicted. Seeing Tanjiro's descendants just living normal, peaceful lives in a modern setting after all that tragedy was heartwarming but also a little jarring. The biggest twist for me was probably Nezuko becoming human again not through some final, epic sacrifice, but through a more subdued, medical process after Muzan's defeat. It felt anti-climactic in a way that I've grown to appreciate—it wasn't about a grand magical fix, but about the world slowly healing.
Another major one was the complete eradication of demons as a concept. I guess I always assumed some remnant or new threat might linger, but the manga commits to it being a definitive end of an era. All the surviving Hashira and slayers get to grow old and pass on naturally, which is a twist in itself for a series with such a high body count. Yushiro being the sole immortal left, painting Tamayo forever, hit harder than I expected. It's a quiet, melancholic kind of twist that stays with you.