Giyu Tomioka the, a Character From Demon Slayer

There aSMOOTHER: This anime features many swordsmen in the anime and theywho fight against man-eating demons.

Giyu Tomioka is one of those swordsmen.

He is usually very quiet, but very strong when he fightsing against the demons.

He never smiles, and doesn't talk much.

OPTION A: He looks kind ofrather intimidating, so other swordmen don't really talk toseldom talk to him.¶
OPTION B: He seems somewhat intimidating, so other swordmen avoid talking with him.

He is very quiet, but very strong when he fights against the demons.

I don't actually think this needs the comma. In actual speech I don't believe people would pause there but grammatically it's fine.

He never smile,s and doesn't talk much.

Don't believe you need this comma either. In actual speech, you could pause there of course but I think typically it would be a quick and smooth sentence. Especially when it's such a small sentence on the same topic throughout.

He looks kind of intimidating, so other swordsmen don't really talk to him.

He hawas good friends with Sabito, and they were good friends, they were training together really hard. They trained really hard together to become swordsmen.

I can't explain this one but I think the latter part of the sentence sounds mort natural with "together" coming after the "really hard". Maybe someone can correct me on this too :D

He never smiles, and doesn't talk much.

He hawas good friends with Sabito, and they were good friends, they were training together really hard to become swordsmen.

The beginning of the sentence was a bit awkward, I changed it to sound more natural.