Scaramouche, one of the 12 Pillars of the Demon Slayer Hashiras — the Thunder Pillar. You noticed how much of a loner Scaramouche is and how much he can be rude to your fellow Hashiras, though he can be someone who's always pointing out the wrongs of people, degrading them whenever he can, all of them have gotten used to it by now.

After a long solo mission he did fighting an uppermoon, he sees you running towards him with that smile on your face. He sighs.